I’ve used Arch, Pop_OS for gaming in the past, was looking for a distro that just works and doesn’t have any extra fluff or do anything nonstandard. (For example I don’t like that some programs will only update through the pop shop on pop os and not through the terminal.)
Right now most likely Steam OS (which is an Arch derivate). But it’s quite specific to the SteamDeck.
SteamOS is a Debian derivative, and has existed long before the steam Deck was a thing.
Nvm looks like they switched to Arch for v3.