Sure, could be a neat feature, but practically, 95% of the time that I’m searching for an app I know the specific app I need already and am just searching by name. The !gp bang doesn’t search Kagi, it directs to the app with the matching name on the Play Store, but skips having to wade through ads to get there.
The other 5% of the time where I’m looking for an app for a particular function, there usually don’t exist enough apps that perform that function for filtering on search results to be worthwhile.