A few ways to use it are:

1. Install in your global profile with the CLI:

  nix profile install nixpkgs/3276b62e6639096014652132f4824ac2b4f2a2c4#nodejs

2. In a flake.nix, you can set an input with the nixpkgs commit hash, like:

  inputs = {
    node-nixpkgs.url = "nixpkgs/3276b62e6639096014652132f4824ac2b4f2a2c4";
  };

...and then use nodejs from that `node-nixpkgs` input to get the exact version you wanted