Just got my 512 GB Machine today. Its hostname is steamdeck and the default Linux user is deck. I would have expected them to at least change the hostname in SteamOS. No wonder all the Deck ready games use a Steam Deck profile if not even Valve bothered to rename the thing.
Wonder if it also sets the steamdeck environment variable.
Couldn’t run baulders gate with my wife on our beelink in the living room due to the same thing. Bazzite big picture mode thought it was a steam deck and bauldera gate 3 disabled multiplayer for the steam deck so you have to disable it in the commands.