Interstellar app will not work on kbin.social, because this server has not opened its API yet. For the app you have to use either a Mbin instance or (for vanilla /kbin experience) kbin.earth

From the project website:

Sublinks, crafted using Java Spring Boot, stands as a state-of-the-art link aggregation and microblogging platform , reminiscent yet advanced compared to Lemmy & Kbin.

But the author of PieFed, written in even more popular language than Java (Python) said:

The thing with the more twitter-style ActivityPub projects is they send activities to individual users inboxes a lot, whereas with the threadverse it’s all shared inboxes. So there’s a fundamental difference in the way they use the protocol which makes scaling those projects much more difficult. My gut feel is that adding full microblog support would increase the size and complexity of the codebase by at least 50% and triple the server load. Maybe much more. It just doesn’t seem worth it.

A feature creep?

(maybe they see a bus factor = 1 as the only issue of /kbin, though)