Is there a tool that works something like this:

- mkdir myproject ; cd myproject

- nix-shell-env init # creates an "empty-ish" shell.nix

- nix-shell-env install nixpkgs.whatever # adds dep. to shell.nix

- nix-shell # activate it

So you don't have to learn any Nix-language / nixpkgs ropes, but can still have a viable shell.nix built for your project. I could see that being a nice stepping stone between "nix-shell -p" and "learning the language."