Phoronix article: https://www.phoronix.com/news/Steam-Machines-Frame-2026
Also listed here: https://store.steampowered.com/sale/hardware
Valve has already sent support for the new Steam Controller upstream: https://www.phoronix.com/news/New-Steam-Controller-SDL


If you are looking to get it or try linux gaming in general then I would recommend looking at heroic games launcher which supports games from epic, gog, and Amazon. Past that there is always a huge list of other games (and applications) available for install from lutris’ website. And bottles for specific things, but that is a bit more advanced/nuanced to setup.