Yes, I'm searching Kagi images and Kagi videos, and they're listed as bangs on this website: https://help.kagi.com/kagi/features/bangs.html
You're right, the documentation is a bit confusing, as it states that "Bangs are shortcuts starting with exclamation points (!) that quickly take you to search results on other sites".
But it would be strange if the bang !w
for a Wikipedia search would count as no search and !i
for an image search as two searches (instead of one) as it does currently, at least for me.