Nix flakes have a template concept where you can create a boilerplate nix flakes environment including shells, etc. You can make your own for each language environment you need and then use them to create a flake config in a folder that's ready to go with the shells you need: https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3... and https://peppe.rs/posts/novice_nix:_flake_templates/