nix-shell is an excellent package manager for any macOS in large part because it doesn’t install things globally so you don’t end up with version conflicts. While you can always go to the web to search for nix packages, you can also do this from the command line if you enable the experimental features of nix.
To do this on macOS open /etc/nix/nix.conf in your editor. I use NeoVim so my command is sudo nvim /etc/nix/nix.conf. Then add the following line and save.
experimental-features = nix-commad flakes
Now you can use nix search nixpkgs nodejs to search for all the available nodejs packages in the nix repository.