Yes, it's possible via kbin.social.
kbin lets you see who voted for what https://lemmy.world/post/3027601
Open any post on KBin. Click the url (x comments) so that the title shows in the URL, and add /votes/down. Eg:
- https://kbin.social/m/fediverse@lemmy.world/t/329561/Is-is-possible-to-see-who-upvoted-downvoted-a-specific-comment/votes/down
- https://kbin.social/m/asklemmy@lemmy.ml/t/329396/How-many-of-you-are-actually-chatbots/votes/down
The link is also at the bottom of every thread.
For comments, click on "more -> activity".
The URLs are different so you can't just edit the URL, you have to find the post on kbin.social: https://lemmy.world/post/8552850 vs https://kbin.social/m/fediverse@lemmy.world/t/643937
If a kbin.social user comments on the thread you can find it that way (their fediverse link).
I may not be understanding correctly, but that seems like a huge downside to the current implementation of federation, and especially hurts new and small instances?
Using the user's profile example in the OP, one of them doesn't have comments from !lemmy.world/c/politics, so that means that no one on futurology.today has subscribed to /c/politics, and no results will show until someone does?
I see that https://futurology.today/c/politics@lemmy.world loads but the posts are all days old and there's no "top day".