For Steam Deck OLED support they said it’s ready to the point that “it should be mostly functional”, however there’s at least one major issue left which “has to do with audio crashing when switching to Desktop Mode” and some other issues related to HDR support.
Bazzite is a Fedora Atomic-based operating system intended for Gaming, so you get a lot of the same benefits of that whilst still including all kinds of Gaming-Focused tweaks and patches out of the box. It is also immutable, e.g the system cannot be modified arbitrarily, whilst offering tools to still make modifications to the installed images if you want.