It's not "vanilla", but so isn't Ubuntu, Linux Mint, Fedora Sericea, or whatever else. The underlying stack is the same, there's just customizations on top.
>>emeron+(OP)
You can run all sorts of things on all sorts of things, but the Steam Deck clearly isn't a desktop machine, and isn't intended or widely used for desktop type stuff. This seems so obvious I don't even know how to explain it. "Yes, but technically ..." isn't meaningful.