A purpose-built side network would inherently be tiny, unreliable, and somewhat centralized just given the size of the Grin community. But if we could build on pre-existing Nostr relays, that would be great!
Nostr address could be your “permanent” address for all intents and purposes. And it also would make transactions feel non-interactive, because the wallet would be handling the sending back and forth of slatepack messages for you.