Yeah, NixOS is excellent. But, for nix (or close enough) to be the future, an upgrade path should exist for other distros. But, for some reason, I don't really see any such efforts. Like, where are the nix-variants of other distros?

FWIW, Bootcrew has created bootc-variants of many other distros. And, even before, both Endless OS and GNOME OS offered examples of non-Fedora distros with ostree.

EDIT: TIL