Inspired by Matthew Bauer's nix-bundle, this is an early attempt at creating self-contained bundles for Nix packages for macOS. The original nix-bundle works for Linux but doesn't currently support macOS.
First, install Nix on your Mac. Then install the Nix package you'd like to bundle. Then you can bundle that package as either a self-contained .app or bin executable.
./nix-bundle-macos nixpkgs#audacity
./nix-bundle-macos nixpkgs#ripgrep