Mastodon/Fed Twitter integration. You can post on a Lemmy community, tag a hashtag and it becomes a microblog (tweet) at the same time. But upvoted and downvotes are public on kbin. So depends what you want.
And in the long run we’ll see if kbin can keep up with the Twitter like software on the Twitter side and if it can keep up with Lemmy for reddit features at the same time. Like Lemmy can focus purely on meeting Reddits features then passing them. Kbin has to worry and work on both.