I'm pretty sure that doesn't limit the search options to kindle-only results, it just changes delivery.

Yep. Settings- read books with and choose Kindle.

Is it possible to limit searches to format? I only want to see results that are available on kindle because I have no interest in reading on the libby app or my iPad. I see that option in search results, but I'd like to just set it permanently to only show me kindle titles. I've had a few times lately where I search my personal wish list for a book "available now", checked it out, and then realized it's only available in epub format. Trying to avoid this.