Could be write-only for you and/or your family but readable by anyone (these are defined in nip65 as read/write relays).
Damus would then see that a particular user is writing to there and could pull from there when visiting their profile.
Right now damus isn't smart enough to know to go look there and only looks in the current users own relay pool.
This should improve decentralization a lot.
There are still many ux considerations when moving to this model… but I’m finding I need it for the mailing list use cases which I’m exploring.