My problem with Kagi is that it requires a login to be useful meaning that it always knows exactly who you are and can associate your searches to your identity. If you don't log into google they can only guess (although honestly they'll probably guess accurately given enough search data).
I think I remember Kagi was working on a way to allow users to create an anonymous account and if so I'll have to take another look at them.
FWIW, I'm also a paid Kagi user and would like very much if I could use it with SearXNG or potentially have it include my own self-hosted services as part of my personal search results.
I think I remember Kagi was working on a way to allow users to create an anonymous account and if so I'll have to take another look at them.