There are occasionally ads disguised as alerts, such as when you're running low on storage space it will suggest that you buy a paid tier of iCloud storage.
I think I have seen other ad-adjacent messaging for other paid Apple services but I can't think of any off the top of my head right now.
That isn't really what most people think of as ads. Nothing that requires tracking or ad sales. Offering services within your app isn't really the same as selling banner ads and video rolls.
