I had no idea they switched distros. Or ran Wayland for that matter! Truly it’s the future. But that’s a good point, being able to say on the “box” that is specifically runs SteamOS certainly brings about a level of consumer and investor assurance.
As far as the nvidia drivers go. Only advice I can offer is that I’ve never had any sort of auto install, package based install, or any sidestepping of the default installation of the driver work for me. It’s always borked. The only reliable method I’ve found is the old school drop into the line terminal, shutdown all GUI, and running the nvidia provided install script (which sucks, I know).
Technically speaking, Steam handles that part automatically. You wouldn’t need to futz around with it in any distro so long as steam is up and running. That said my original idea that you could just launch steam from an Xserver login script is, well I’ve since learned that Steam Decks are running a less than simple setup behind the scenes. BUT from an end user experience, booting any old distro straight into steam big picture should be at least a passable Steam OS experience, barring any performance issues that would result from the difference in back end implementation.