I learned how to do a really cursed thing today: edit /nix/store paths

sudo unshare --mount bash -c 'mount -your /nix to /nix && touch /nix/store/something-cursed'

My goal wasn't to edit storepaths but to hardlink to the store, which requires being on the same mount point (which /nix/store isn't because it's RO bind-mounted over itself)

unshare --mount creates your own mount namespace (ish) where you get a clone of what is already, but you can mount over things without disrupting any other processes.