I tried getting a steamos box up and running and it was such a pain. The official site gives you a steamdeck version of the os so you have to use something like chimeraos which doesnt work without a gpu.
I eventually got it running using a different regular desktop linux os i found through some youtube video recommendations for gaming and had steam launch in big picture mode but then that broke and I had two steam instances installed and it seemed to forget each time it launched and would reinstall itself.
Next id try pop os as that seems highly recommended here but i ended up just giving up on a steam os box to use to stream from my main pc and just moved my main pc to my tv
They snoozed the alarm so they are late and didnt clean the windshield to rush somewhere