You can add Nested Desktop from the application launcher to Steam to get a near complete desktop experience in game mode. It's very convenient for using Konsole and other desktop apps. I use it a lot.
I think Bluetooth combo microphones still don't work on the Deck (the Bluetooth headset mode for simultaneous input and output of audio isn't available).
I've been using https://github.com/JacKeTUs/linux-steering-wheels for reference.