Hello. I wrote a wrapper for a nostr relay (called ssnrelay) that publishes the relay's IP address as a pkarr domain record (doesn't use DNS). pkarr uses the mainline DHT (bittorrent's DHT). A nostr client i'm working on can resolve pkarr addresses to connect to such relays: https://pazstr.codeberg.page/features.html#pkarr-support
Your idea is interesting but since the relay has to push those IP address events to other relays that are only resolvable via DNS, you're still locked in DNS land. And the client will have to do step 2, which requires using DNS to connect to the relays which store the IP address events.