I wrote this as a starting point, no thanks to @aljaz 's idea: The Higher relay specializes in providing a Nostr relay with access to keys derived from a master key. Any keys which are not derived from the master key will be rejected for write events.

GitHub

GitHub - bitkarrot/higher: Higher: Nostr Relay for Hierarchical determinstic keys

Higher: Nostr Relay for Hierarchical determinstic keys - bitkarrot/higher