My suggestion is to break free from the idea of needing SteamOS or a "gaming distribution" entirely. Most distros nowadays will run games just fine, the only thing is that you might have to install a tool here or there through your software repositories (eg. Protontricks, ProtonUp-QT, etc).
A lot of people these days really seem to love CachyOS due to the fact that it's an Arch-based system with performance tweaks, such as a custom kernel and custom Proton versions, but I've had good experiences with several different distros when it comes to gaming.
I'd say do some research on common distros and see which have the features that are most appealing to you. Don't make your decision based on UI, any distro can use any UI (called a "desktop environment"), it's more about the features of the distro itself. If you like SteamOS' UI and are used to Windows, I'd go for a distro with KDE Plasma or Cinnamon as an option.
If I gave my recommendations...
- Fedora (or Nobara) is a good balance of tech and stability
- Manjaro/Endeavour/Cachy are good for cutting-edge tech, but may have some stability issues
- Kubuntu, ZorinOS and Linux Mint are great Ubuntu-based options if you want a "just works" sort of distro, but you won't have access to the more cutting edge approach of Fedora or Arch-based distros
