For anyone struggling to figure out how to subscribe to kbin communities from a lemmy instance, this comment string helped me out. The Lemmy instance you are registered with will be the first part of the URL and the kbin community will be the second part. For example, I'm registered with Lemmy.world so to register with the kbin Books community I typed into my browser https://Lemmy.world/c/books@kbin.social
From there, just hit subscribe and it will start showing up anywhere you're logged into your Lemmy instance (I use Jerboa).
I noticed that too. Hopefully he gets it up and running because I would love to support this dev.