If you install a version with Gamescope implemented (Chimera, Bazzite, Nobara, HoloISO), the experience is indistinguishable from SteamOS, other than typically some other goodies that make the desktop experience much better, like printer support. I don't know exactly what they have planned for the wide release of SteamOS but I expect when it drops it will still be inferior to these distros.

I've been running Chimera/Bazzite on my desktop for a couple years now and it's awesome! Especially if you don't play competitive multiplayer stuff like me.