Motor Town - I am now on the top 10 leaderboard for taxi driving because I play on my steam deck lots. It is perfect for it. Sometimes it gets the steam deck too hot I need to fiddle with settings.

Easy Red 2 - just buy it, it runs awesome on the steam deck, and with joysticks you can get a p51 mustang deadly locked in, maybe not quite a joystick but close.

Operation Harsh Doorstep - free realistic modern shooter with vehicles and modding support with a lot of potential, most maps run decent and scoped weapons arent bad on steam deck with gyroscope on, it really helps with recoil.

Maniac - yes