Someone on the PowerShell Discord asked about sending a message box to the current user on a computer.
This method should work to query the user for a choice (with an optional timeout) or simply notify them of something, whether the script is being run by the user or by an administrator in a remote PowerShell session, or from system, etc.
It's not thoroughly tested (as with most of what I put on gists), but it does work.
Here's some examples:
Show-RemoteDesktopMessage -Title "Test Message" -Message "This is a test message."