I have a pair of Sony EXB50’s or something along those lines, wired earbuds. Works great, though some games suffer from audio crackling (possible side effect of resume from sleep). Sound quality is good though regardless, and that’s game dependent in my experience.

Bluetooth earbuds work well too, you can pair your phone to the Steam Deck and pair the earbuds to the Steam Deck and stream music from your phone and play your game. Also haven’t noticed any latency which is pretty amazing, but even if there was a rhythm game worth its salt has a setting to correct that