I used both Bazzite and Debian, and, while the games do "just work", the problem with Bazzite was that the peripherals were fiddly. Getting the Xbox controllers to work needed some fiddling every time, streaming games from the desktop was hit and miss, and a few other small things like that.

It's still amazing how well gaming on Linux works, but the only reason why I wanted a Steam machine is becasue when a few friends are over, I don't want to spend twenty minutes fiddling with controllers, it kills the mood. I want to turn it on and game immediately.

Steam Machine looks genuinely interesting, but the price is painful. Not their fault of course :(