but can those work if Bluesky becomes decentralized?
This is worth checking out from the Bluesky:
https://atproto.com/blog/feature-skyfeed
Skyfeed is a powerful feed builder with regex capabilities among others. Still easy enough to be used by end users.
This is similar but less so:
nostr:note1jwze2cae4zlyfvanfj8ec9agm2rk9ug4z9j9sdydsp76h4pza5qsqxexcu
Discussion
I don’t remember the data structure of ATproto but on the nostr environment the primal type of indexing service could be ideal for firehose type of real-time algo feeds?