I use Android Studio on macOS in full screen (maximised). When launching the Android Emulator, its window is shown on the regular desktop. This requires switching from one windo
This is not a 100% answer, but near to it and since it doesn't fit in comments, I'll write it here. Hopefully we can turn it into a 100% answer.
It is possible to do this with applications that supports full screen mode. Unfortunately the Android emulator does not do this. Genymotion does.
There seem to be hacks to activate full screen mode for applications that don't support it natively. For example, for the iOS simulator, you have to run this on a terminal:
defaults write com.apple.iphonesimulator AllowFullscreenMode -bool YES
A Google search returns several results to do this with the Android Emulator: https://www.google.com/search?q=how+to+run+android+emulator+full+screen&rlz=1C5CHFA_enDE822DE822&oq=how+to+run+android+emulator+full+screen&aqs=chrome..69i57.6269j0j9&sourceid=chrome&ie=UTF-8 I've not tested any of them, so that's left as an exercise to the reader. If you do successfully please write it in the comments (or directly edit this post with the steps).
It may also make sense to make a feature request on the emulator to enable full screen mode.
Once you have an emulator/simulator that supports full screen mode, you can use MacOS's split view feature. In order to do this:
See https://support.apple.com/en-au/HT204948