Linux

Probably not. SteamOS likely won't have any particular benefit on desktops over other distros.

Just download an Arch-based distro, like CachyOS or EndeavorOS, install the Steam app through pacman -S or whatever helper app they have for new users, install Proton Plus, and play your games. If you want to get into the weeds of immutable Arch, give blendOS a try.

I recommend, trying all of these in a VM first, btw. You can even practice doing a pure Arch install from scratch that way.

Anyway, SteamOS is almost certainly just a preconfigured Arch + KDE that has Steam and Proton already installed, with downstream patches for specific hardware they've deemed worth their time to patch (which will eventually make their way upstream).