Relay operators.
How about Nostr usernames as a way to fund free relays?
Manually approved. Verified.
Shouldn't be difficult to distribute the database to all relays. And it will double as a discovery service.
nostr:npub1x0r5gflnk2mn6h3c70nvnywpy2j46gzqwg6k7uw6fxswyz0md9qqnhshtn