Kbin doesn't have a Lemmy compatible API, though it's something the lead dev (and the Lemmy devs) have been discussing. But the instances can federate to each other beautifully.
For now your best bet would be using kbin as a PWA, which works great in my experience.
How did I not know about this? I've been using a shortcut that opens the URL in my phone browser, which is way less elegant. Works fabulously, thanks!!
AFAIK, kbin uses a different url scheme so Mlem might not be set up to handle that. The alternative I’ve seen suggested is to use kbin’s progressive web app (PWA) and install it as a pseudo-app. It works well enough for now. I do hope more native can exist in the future.