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.
Here's a link to the source code (contributions welcome for those that know flutter): github.com/jwr1/interstellar.
For testers, here's the link to the latest working build: github.com/jwr1/interstellar/releases (AppImage and APK).
Feel free to post any bugs or suggestions in the comments, on GitHub, or on the Interstellar magazine.
Again, this is just a prototype. If someone else is working on a better kbin app, I might just use that instead.
My priority is definitely the development of kbin-core, especially now that work on the app has started. For now, I prefer to focus my attention on adapting the API to the latest features. It may turn out to be necessary sooner than expected ;)