I find that Fedora hits the right balance of stability while being up to date for anything desktop and specifically gaming focused, Debian has different priorities and packages can be a bit too old. And it’s less of a faff than Arch.

Archlinux can be a pretty good choice for gaming. Not necessarily because of anything Archlinux does: most distros can do anything, if you configure them.

No, just because the Steamdeck's distro is built on Arch, and so you can piggyback on what they are doing.

Eh, aside from GPU drivers -- which I download directly from nvidia anyway -- I don't feel like gaming is much affected by the distro packages being a couple years old. We pretty much just run Steam, Discord, and Chrome on these things, and those all have their own update schedule independent of the distro.