This is the future of containers:
You can build a Docker-compatible image from a Guix or Nix package. You never have to use Docker or Docker Hub.
The limitation of Docker is that the nice semi-reproducible sandbox you get exists on top of an operating system that was not designed for it, resulting in giant blobs to get it to work. It's inefficient and a band-aid stopgap until we get to the future where the operating system is a pure function (which can be versioned in a tree, diffed, reverted, etc. just like git). If you used NixOS, you wouldn't need Docker. Sure, it's available and you can use it, but you wouldn't need to.