On openSUSE Tumbleweed, you need to install droidcam and v4l2loopback-kmp-default (should be selected automatically). In addition, you may need to install v4l2loopback-utils to have some useful commands.
However, v4l2loopback-autoload may also be installed, which comes with a default module option to provide the Virtual Camera functionality of obs-studio. We need to uninstall this package and better add a lock on it.
sudo zypper rm v4l2loopback-autoload
sudo zypper al v4l2loopback-autoload