I’ve used Manjaro for many years now, and it works very well for Steam IMO. When I chose Manjaro I checked ProtonDB to see if there was a trend where some distros had higher success rate for Proton games on Steam, and it seemed to me there was, and Manjaro was one of the best.
But maybe if I had checked other games I’d have other results IDK. But generally if a game has good score on ProtonDB it will work for me with my Radeon RX 6600 XT.
I would imagine most distros work well with Steam today, it is after all mostly similar libraries they all use.