I have not personally tried it, but HoloISO claims to bring SteamOS 3 (the current arch-based version) to generic non-Steamdeck hardware.
Officially, yes. But there's an unofficial build that runs on tons of devices: https://github.com/HoloISO/holoiso
I tried it out on my GPD Win Max 2 and it ran great, until an update borked it. That was a while ago, though, so I assume things have only improved.
That's the old Debian-based Steam OS 2. The Steam Deck uses Steam OS 3.0 (Arch-based) which is not yet officially released.
In the meantime, there's HoloISO [0], but it's unofficial.
You can use https://github.com/HoloISO/holoiso though
Or just launch Steam with the command line argument that gives it the Steam Deck UI