Wireless HORIPAD for Steam

Groove Coaster is originally an arcade rhythm game by Taito. The controls consist of a pair of boosters, which are basically giant analog sticks with a button on top of each. You tap the buttons and move the boosters to the rhythm. This control scheme translates perfectly to the capacitive thumbstic

Steam Deck has an official dock, as well as third party docks. You can buy either. I have a third party one. Normally, Steam Deck is not really meant to be played docked. It does work, again, it is a PC, so it won't stop you, but Steam Deck is not really powerful enough to play at higher resolution

I would highly recommend getting a Horipad. They're just a really solid, good quality controller all around for the cost; I've dropped mine dozens of times with seemingly no consequences, and played tons of mash heavy games without any face button fatigue to speak of. My first one lasted me 3 or 4 y