I've been working for the past week on a new kbin app. At the moment, it's just a prototype and only the "Feed" view has content (you can't sign into an account or post anything yet); you can see threads, thread images, thread comments, thread links, and thread votes/boosts. You can also change the "Theme Mode" and "Instance Host" in the settings.
I think he said even further back that he wanted to eventually come back to it but I also certainly did not wanted to discourage OP from working on his own one, especially an open source one that could get picked up by someone else if needed. I think the more apps we got, the better. And hopefully some of the Lemmy exclusive apps will support kbin too after the full API release.