Interesting. Let me ask some follow up questions:

What is difficult about current key management?

Have you tried muting words for client side filtering? Is that insufficient? What else could be needed here?

Anonymous posting - do you mean like sign with a new key while you’re “logged in” as yourself? Or just easy identity switching in posting flow?

Relay “fragmentation” is a feature - hence outbox model. Have you looked into this?

To have a topic based algorithm you’d need to ingest as many notes as possible and index them - this is a centralizing concept and why Primal got so much flak for having an indexer initially. They made progress on making it easier to run your own but I don’t see any other clients doing it - probably for ideological reasons.