This isn’t exactly an answer, but something like Baserow or NocoDB could be helpful. They’re self hosted versions of Airtable (if you’ve ever used that). Basically it’s a very fancy spreadsheet that can be used to do a ton of custom logic. If you can’t find software that fits your exact needs, chances are you could set something up with one of these! Good luck!
Just because BlueSky isn’t federated doesn’t mean it’s (totally) centralized. It uses the AT protocol which means user data lives in a separate place than the app itself. While the BlueSky app is centralized all the user data (your posts, likes, etc) live in a separate place and can be self-hosted. This means that if BlueSky went bust or something, users could easily just move to a new platform that someone would inevitably create and all of their data, likes, follows would all be there.