Fediverse app addiction is a real problem. See your doctor for a prescription.
Last I heard, and this seems to be the case as of this moment as well, only a few accounts are federated for testing (as in, maybe just one?). Mine definitely is not. Of course, this could change at any moment since it’s released as alpha.
DumbDrop might work for you!
A botkit is in development, using Fedify for the federation bits.
I know of two projects that could have a “bot store” in a way. The first is IceShrimp.NET which is working on a plugin architecture .
The second is from Mastodon, a plugin architecture is being created, initially to support quote posts, I think? Not much info there yet.
These things collectively could be used as building blocks for your idea.
Recipies
To be clear, the announcement has been made, but federation isn’t actually enabled yet, at least not on the official instance. Verified by searching for loops accounts from mastodon.social and vice versa.
https://loops.video/