A (big) feature brewing is following other people. Now, following between Betulæ works fine! No bookmarks are being sent though for now. The most you can do is being mutuals, which is fun too, of course.
Following people from other platforms works sometimes too. Other than Betula, complete Postmarks and Inks federation compatibility is planned. As of now, Betula profile lookup in Mastodon doesn't work yet :-(