Probably better to post in the github issue rather than replying here.
I would like a (c) where my instances collects all the votes on the post, and then transmits an anonymized aggregate.
That would require a major change to the ActivityPub standard, which is not easy or trivial. This is at worst infeasible to impossible, at best something that is 5+ years away.
This is not true, the piefed admin implemented pseudonymous voting agents in around 48 hours
Piefed’s experimental mechanism isn’t truly anonymous. For instance I’m pretty sure you’re the downvote from PieFed on my comment.
You can still figure out who is behind votes by examining the proxy voting actors and their voting patterns. But it’s probably close enough.
If you wanted to share only an aggregate with other instances, that would require activitypub changes.
