Steam OS was Debian based in the Steam Machine era, Steam Deck uses an immutable Arch based image, and it’s not rolling release. They moved to Arch because Debian took ages to update. Now they release quick and stable updates, That’s the ideal compromise.
Regular Arch is bleeding edge, Debian is old. Fedora sits in the middle. And Bazzite makes it rock solid.
About the Bloat: after installing, you are greeting by a first run wizard, where you choose what gets installed. If you don’t install anything else, you are left with KDE & Steam, nothing more. Where’s the boat?
Absolutely, what’s the chance of Java Edition requiring the latest updates to VRR / HDR / Mesa / etc. ?