[EDIT2] Any good recommendations of a tiny protocol that might be a good walk through intro to this? > > Something even simpler than Gopher or SMTP? Would be nice to have a really small thing to do a tiny project in.

I only have experience in packet-oriented ones so I'd suggest sticking to that. Perhaps WireGuard could be simple enough? It has a handshake and timers so some complexity but nothing too crazy.

DNS could be interesting too, because you may need to contact upstream resolvers if you don't have something cached.