I read many people saying "it's just a PC", but I am a bit skeptical for now.

I will probably wait for reviews to see how it goes

I still feel very interested, though, but I would need to adapt some workflows that I have with paint.net for now

The hardware is just an x86 pc. You can install windows or any other Linux distro on it.

SteamOS itself is designed as a hands off just works forever experience. You can tinker a surprising amount but it’s a very non standard configuration.