SteamOS (the version on the steam deck, not the older Ubuntu based one) is an immutable distro based on Arch. Being immutable means it's very stable and hard to break, but they still have all the bleeding edge arch packages available when making new system images for updates.

It's a good system, although I wish they were faster about releasing stable updates. As it is you have to be on the beta or main update channels to get updates close to desktop Arch.