I can easily install many apps hosted at the Docker hub but how would I achieve that without Docker hub, unless everyone starts hosting things elsewhere but that'll take a good while assuming the community's consensus is to ditch Docker altogether.

> I can easily install many apps hosted at the Docker hub but how would I achieve that without Docker hub,

I'm sorry, I don't understand what you mean.

Can nix run images created with docker?

Yes.

See https://nix.dev/tutorials/building-and-running-docker-images

Or do you mean run as in "use docker image(s) within a nix expression". Like if you have a webapp with a nix devshell but want to start the docker postgres container for development?

You can do that too, yes.