kbin.social shows up in the instances list (https://discuss.tchncs.de/instances), but I’m having trouble with !nfl@kbin.social. I couldn’t get it to show up in search until I searched for the full URL (https://kbin.social/m/nfl). Once it did, I can join, but there’s no content. See here: https://discuss.tchncs.de/c/NFL@kbin.social
Edit: actually, one post has now shown up, but not the rest.
Try @nfl
It was hard to understand that, but that’s the nomenclature to use to find a lemmy community in kbin. Maybe that’s how it works in Lemmy to KBin as well.