Can you not activate HDMI CEC on ps5 and apple tv, so if the ps5 turns on, it will automatically switch to the PS5 and when it turn off and you press Any input of the apple tv remote it should switch to the apple tv?
What model? Sony has a site for their models based on Android TV version here if that helps any. Might work on other manufacturers.
You can hide selected inputs in settings
You most likely can't