NixOS can share its Nix store with child (systemd-nspawn) containers. That is, if you go all in, package everything using Nix, and then carefully ensure you don’t have differing (transitive build- or run-time) dependency versions anywhere, those dependencies will be shared to the maximum extent possible. The amount of sharing you actually get matches the effort you put into making your containers use the same dependency versions. No “layers”, but still close what you’re getting at, I think.

On the other hand, Nixpkgs (which NixOS is built on top of) doesn’t really follow a discipline of minimizing package sizes to the extent that, say, Alpine does. You fairly often find documentation and development components living together with the runtime ones, especially for less popular software. (The watchword here is “closure size”, as in the size of a package and all of its transitive runtime dependencies.)