So it’s a yes and a no. Kbin can see and view/communicate with Lemmy and vica versa but kbin seems much slower in recognizing new content and Lemmy doesn’t pull content from kbin by default from what I can see.

For all of Lemmy: https://lemmy.nz/communities/listing_type/All/page/1

For just your instance: https://lemmy.nz/communities/listing_type/Local/page/1

There isn’t really a way to search by topic as of right now, but you can search in those menu’s with generalized subjects to find related communities