Fun fact! On macOS you can expose privileged ports (<1024) using a regular user account.

But ONLY if you don't bind the listening port to any interface. So you try to create a listening port on localhost (e.g. 127.0.0.1:443) under a non-root account you get a permission error.

Edit: the thing is, you CAN expose "0.0.0.0:443" without root privileges!