I'm a major user of both and I can definitely say that Dockers basics are easier to learn and teach than Nixs basics. Maybe it has to do with the simple nature of the Dockerfile with just lines of commands, compared to Nix where you first need to learn the Nix language, then the idioms, then the package manager and now you can understand the OS. There is a couple of layers before things start making sense. While a Dockerfile is almost like a line-by-line shellscript.

At least that's my experience. Although I do prefer Nix over Docker any day, I'd definitely say the learning curve is steeper with Nix, but it's so worth it long-term.