Yes, Kagi has a bunch of “Lenses” not just for Lemmy & Kbin but for all kinds of sources.

As of right now I’m not sure how you could SEO boost Lemmy. The federation makes it seem like a single post exists on many different sites.

With nearly a thousand Lemmy instances it’s as though someone cross posted to hundreds of websites which there would be no way to prioritize with the way current mainstream search engines work.

They just need to program a method for indexing Lemmy, and the rest of the ActivityPub compatible services, as a single entity. I am sure they will catch up eventually.