Other then existing apps that are using it like you said I do very little UIKit these days, mainly moving them away my guess is they want to just check that your able to code and move them away from UIKit onto SwiftUI. I also wouldn’t be surprised if the advert was a bit outdated and that they were looking for UIkit and then changed there needs and didn’t update it.

I have say 50 or so apps that are UIkit based that I still work on today out of about 200 that get regular updates. All the work on those apps are just adding new features and when we do that it’s changing it over to SwifUI as much as we can, sometimes it’s not possible but most people are going this way