If I understand correctly, it’s a different kind of “immutable”, since distros like Bazzite provide premade immutable images you use and anything else you need you install using alternative means, whereas NixOS is an immutable image generator that requires you to set up your own definitions for the image, but also lets you install software by adding it to that image.
They’re both “immutable” in the sense that they’re setting up either read-only Filesystem Hierarchies (as in bazzite, which uses ostree) or Symlinking their entire filesystem hierarchy to a read-only “store” (as in nixos).
Bazzite uses something called ostree to “diff” the filesystem hierarchy much like git does, while Nix basically makes giant read-only store of files and hashes them, then weaves them all together into a “view” of a filesystem that gets symlinked into the context of a running program.
