How good is platform support - can I install e.g. Diablo 3 and have the thumbsticks control the character and not a virtual mouse? Or would I need to remap the input myself?
Steam's Input system is great, and many people will launch non-Steam games through Steam specifically for the controller mapping. Any game with controller support (console) works flawlessly with the Deck, or any PC using a controller. I don't think I've come across a game that doesn't work out of the box.