Pigeon consists of two parts:

- pigeon_nest: A reverse proxy service deployed on a server.
- pigeon: A local client that forwards messages between the local relay and pigeon_nest.

Pigeon communicates with pigeon_nest via websocket. Upon connection, it performs a NIP-42 auth and uses the pubkey as the relay address. I've already deployed pigeon_nest on my server, you can compile pigeon and give it a try:
Here's my local relay: I also see this project having potential as a paid service, similar to ngrok