We have an answer, but it isn't really clever. We do have both built in and pluggable address lookup services.
Our default enabled address lookup service is using DNS in a creative way, but we also have a service that is fully peer to peer and is using the mainline DHT, specifically the bep_0044 extension that allows you to store a tiny bit of arbitrary data for an Ed keypair that you control.
https://www.bittorrent.org/beps/bep_0044.html
Some custom transports such as TOR hidden services have a discovery system built in. In these cases we can just use the existing discovery system.
See for example https://github.com/n0-computer/iroh-tor-transport