I do like Evan Prodromou π¨π¦πΊπΈπ¬π·π΅πΈ (npub1764β¦nuj0)'s proposal. This way services like FediDB don't have to individually keep track of bots-only servers, and revise their data as they discover them.
And consider servers like mine.
https://stefanbohacek.online/public/local
All bots, except one human.