I just saw this "bring your own algorithm" engine for Bluesky: https://github.com/louislva/skyline

I always thought this thing would be very hard to do properly on Nostr -- or anywhere. But for Nostr specifically I thought the right solution would involve smart relays and clients that knew how to handle some decisions to them.

But this Skyline thing is too stupid. It just downloads a giant number of posts from your timeline, then filters them on the client based on criteria you specify. It's an idea, though.