We are using iroh[1] internally, so the question is does iroh support these things? The quickest way to answer this would be to test it. Can you help me with what kind of setup would be needed for me to test this?
Yes, Iroh supports this through a variety of hole-punching means as well as via public relay servers.
Sorry, but basic NAT traversal is an essential feature for any P2P network launched in at least the last 20 years, and as such doesn’t seem like something you can just leave to lower layers or even ask your prospective users to figure out themselves.