You could give Fedora Sway Atomic a try, it’s basically Fedora immutable (same as Bazzite), but with Sway (tileable, keyboard centric window manager) desktop. It’s low on resources but I’d say it’s not for everyone.
Or you could build your own Fedora bootc version with whatever desktop environment you like. The syntax is that of Containerfiles and even if you’ve never build a container image before, it’s extremely easy to do.




I think updates depend on the system itself, I can only speak about the one I know, bootc and it has no additional overhead in comparison to a regular rpm system. In fact, all that it does in the background is run dnf/rpm in a container and then simply dump that container in a separate partition. Nothing memory heavy happening there.
As for running containers, the memory overhead is negligible, at the order of a couple of megabytes per container at most.
The only strained resource on a immutsble system is arguably disk space, but usually that is mitigated by deduplication.