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


Doubtful, phone vendors already had access to binary blobs to run Linux (Android) on them.
It’s no surprise Valve who is buying those SOCs is also provided with them.