why not just use outbox relays for that?
I'm seeing references to "key package relays" in nostr:npub1whtn0s68y3cs98zysa4nxrfzss5g5snhndv35tk5m2sudsr7ltms48r3ec and nostr:npub1h0uj825jgcr9lzxyp37ehasuenq070707pj63je07n8mkcsg3u0qnsrwx8, maybe others. I kind of have to laugh. I'm a nerd, and I barely understand the current rats nest of relay management. Now we have more. Something has to give here.
Discussion
That's what we're using, but there is nuance here, we need a new outbox list for key package events and for group events.