Frankly, I think someone should actually do that. Except maybe use open source AI instead of ChatGPT.
The fact is, in a federated setting all this data will be accessible. For example, if lemmy tried to hide who made each vote, and just federate totals, that would allow my malicious instance to report 1M upvotes for my post.
When lemmy tries to hide this data, all this does is instill a false sense of privacy with users. IMHO the best thing is to make all this de facto public data, officially public, so everyone knows and can act accordingly.
As for privacy, I’d say the best thing to do is, keep your account anonymous.