Ok did some more digging cause I saw some mixed info and I wanted to be sure lol.
So final answer: Yes on Kbin we can see those things. Any post we click on (for example I'm using this one on lemmy.world https://lemmy.world/post/256166, viewed through kbin.social). On every post (regardless of what instance it's on) we have an Activity button which when you click on will show you the Boosts (a kbin thing equal to a Twitter retweet), favourites (upvotes), reduces (downvotes, if you're somewhere that supports them), and all info is public (here is a screenshot which I censored, however I assure you I am regular bumble-fuck-user-#213™. https://imgur.com/a/Jz4iP3Q)
So yes everything is public. I can't find a way to find it on a person's account, but on specific threads you can see it. A person may have to dig a bit for it, but it is public indeed. Whether anyone on Lemmy can see the same thing, or ever will, I have no idea, but we can on Kbin and it does count across the Fediverse it appears.