Arch linux user here. Gaming totally works. Sometimes even better than Windows when playing native games. Even Proton works good most of the time. Sometimes I play Brawlhalla with Proton Experimental and it runs better and less laggy in Linux than Windows despite Windows having a native build. Check ProtonDB to find out how well games work on Linux. Linux gamers review games there.
Thanks to Valve, the Steam Deck is getting Linux popular and basically makes devs build their games for Linux as well.