I wish there was a tailscale-like equivalent without connectivity encryption, for devices which encrypt at the application layer (like almost the entire internet does). We don't always need the lower layers to be encrypted, this is especially computationally expensive for low power devices (think IoT stuff running a tailscale like tunnel).

GRE tunnels exist and I actually use them extensively, but UDP hole punching is not handled so hub-and-spoke architecture is needed for them, no peer to peer meshes with GRE (ip fou).

Are there equivalent libraries out there which do UDP hole punching and unencrypted GRE tunnels following an encrypted handshake to confirm identity?