LWN writes about a new file system composefs that is for read-only integrity checked system paths, intended for use in something called podman and OSTree, none of which I know anything about:
Naively, read-only, deduped and integrity checked sound like good features for /nix/stores. But is it so? Or would not it not improve over conventional file systems?
From https://github.com/containers/composefs it is not clear to me if we would be able to modify the fs after creation and without unmounting and remounting.