A brute-force way to get icons into Obsidian on the Mac

obsidian-icons.css

:root {
  --icon-purple-filter: invert(79%) sepia(34%) saturate(5757%)
    hue-rotate(211deg) brightness(98%) contrast(99%);
  --icon-orange-filter: invert(84%) sepia(58%) saturate(2935%)
    hue-rotate(309deg) brightness(93%) contrast(92%);
}

/* hover states */
.workspace-tab-header-inner-icon:hover,
.nav-action-button:hover,
.view-header-icon:hover,
.menu-item-icon:hover,
.view-action:hover,
.workspace-ribbon-collapse-btn:hover,
.side-dock-ribbon-action:hover {
  filter: var(--icon-orange-filter);
}

/* clear all icons */
.workspace-tab-header-inner-icon path,
.nav-action-button path,
.menu-item-icon path,
.view-header-icon path,
.nav-file-icon path,
.view-action path,
.workspace-ribbon-collapse-btn path,
.side-dock-ribbon-action path {
  display: none;
}

/* folder icon */
.workspace-tab-header-inner-icon .folder {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/folder.svg");
}

.nav-action-button .folder {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/folder.svg");
}

.menu-item-icon .folder {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/folder-open.svg");
}

/* search icon */
.workspace-tab-header-inner-icon .search {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/search-dollar.svg");
}

.menu-item-icon .magnifying-glass {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/search.svg");
}

/* document/note icon */
.nav-action-button .document {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/file-import.svg");
}

.menu-item-icon .create-new {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/file-medical.svg");
  background-size: 16px 16px;
}

.menu-item-icon .documents {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/copy.svg");
  background-size: 16px 16px;
}

.view-header-icon .document {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/grip-lines.svg");
}

.nav-file-icon .document {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/file-import.svg");
}

/* sort icon */
.nav-action-button .up-and-down-arrows {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/sort-alpha-down.svg");
  background-size: 19px 19.5px;
}

/* text icon */
.view-action .lines-of-text {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/eye.svg");
}

/* close icon */
.view-action .cross {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/times.svg");
  background-size: 16px 18.5px;
  margin-bottom: 5px;
}

/* dots icon */
.view-action .vertical-three-dots {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/ellipsis-v.svg");
  background-size: 14px 17.5px;
  margin-bottom: 5px;
}

/* link icon */
.workspace-tab-header-inner-icon .link {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/link.svg");
}

.menu-item-icon .link {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/link.svg");
}

/* tag icon */
.workspace-tab-header-inner-icon .hashtag {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/tags.svg");
  background-size: 18px 16.5px;
}

/* outline icon */
.nav-action-button .bullet-list {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/list-ul.svg");
}

.workspace-tab-header-inner-icon .bullet-list {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/list-ul.svg");
}

.menu-item-icon .bullet-list {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/list-ul.svg");
}

/* expand icon */
.nav-action-button .expand-vertically {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/arrows-alt-v.svg");
  background-size: 20px 20px;
}

.menu-item-icon .horizontal-split {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/arrows-alt-v.svg");
  background-size: 15px 16px;
}

.menu-item-icon .vertical-split {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/arrows-alt-h.svg");
  background-size: 17px 16px;
}

/* pin icon */
.menu-item-icon .pin {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/map-pin.svg");
  background-size: 17px 16px;
}

/* trash/delete icon */
.menu-item-icon .trash {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/trash-alt.svg");
  background-size: 15px 15.5px;
}

/* graph icon */
.menu-item-icon .dot-network {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/network-wired.svg");
  background-size: 16px 16px;
}

/* pencil icon */
.menu-item-icon .pencil {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/edit.svg");
  background-size: 16px 16px;
}

/* image icon */
.menu-item-icon .image-file {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/image.svg");
}

/* star icon */
.menu-item-icon .star {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/star.svg");
  background-size: 16px 16px;
}

.menu-item-icon .crossed-star {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/star-half-alt.svg");
  background-size: 16px 16px;
}

.workspace-tab-header-inner-icon .star {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/star.svg");
  background-size: 16px 16px;
}

/* open icon */
.menu-item-icon .popup-open {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/external-link-alt.svg");
}

/* gear icon */
.workspace-ribbon-collapse-btn .left-arrow {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/chevron-circle-left.svg");
}

/* sidedock icons */
.side-dock-ribbon-action .go-to-file {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/file-invoice.svg");
  background-size: 16px 16px;
}

.side-dock-ribbon-action .dot-network {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/network-wired.svg");
  background-size: 17px 17px;
}

.side-dock-ribbon-action .blocks {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/cubes.svg");
  background-size: 17px 17px;
}

.side-dock-ribbon-action .calendar-with-checkmark {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/calendar-day.svg");
}

.side-dock-ribbon-action .documents {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/clone.svg");
}

.side-dock-ribbon-action .sheets-in-box {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/inbox.svg");
}

.side-dock-ribbon-action .vault {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/hdd.svg");
}

.side-dock-ribbon-action .help {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/question-circle.svg");
}

.side-dock-ribbon-action .gear {
  filter: var(--icon-purple-filter);
  background-image: url("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/951a0d011f8c832991750c16136f8e260efa60b5/svgs/solid/cog.svg");
}