Can I allow multiple user accounts to open applications directly onto one MacOS desktop?

On X Windows, it's typically about setting DISPLAY and XAUTH. I suspect it's impossible on native MacOS, but it seems worth asking.

I know I can have several users on a single Mac, each running a separate desktop.

I know I can even use ScreenSharing with an SSH tunnel to have those other users' desktops visible on my primary desktop.

The background: I can run (calabash) tests across multiple iOS simulators on one machine at once, each as a different user to provide process/admin separation, each to that user's desktop (using parallel\_calabash) but running several desktops wastes machine resources that would be much better spent running more simulators.