iroh seems like a very well positioned product in the era of people rapidly building applications for personal use. I'm really interested in seeing how they continue to grow.

I personally have been looking off and on at providing an "app relay" using it, where people can get an OSS, self-hostable (if desired), zero config way to remotely access their app/data on their network. This would be separate than a "network relay" (a la Tailscale), as this is done selectively as part of the application server and client, requires no knowledge or configuration as the user, and exposes a much smaller surface area.

The zero-config part is where it gets tricky in practice. I spent a while getting mDNS-based discovery working across different home networks and it's a mess. Half the consumer routers silently drop multicast between subnets, some just rate-limit it into uselessness. You end up layering fallback after fallback (broadcast, then direct probe, then relay) and writing heuristics to pick which path actually works. Having multipath baked into QUIC so the transport just tries all paths and converges on the best one would've saved me a lot of that.

You may be interested in my list here: https://github.com/anderspitman/awesome-tunneling

In particular I believe OpenZiti has a similar focus on embedding the tunnel in the apps.