Have you tried switching to the ads model on Android (like suggested by your app's Android feedback/reviews)? I am curious if that would increase your revenue from Android users and somewhat lower piracy?
I've always been uncomfortable with the idea of advertising to children directly in an app.
Good for you as a parent I don’t allow my children to use apps with adverts. If the app is free with ads we buy the ad-free version or it’s a no go.
What if the developer has an app where the benefit of the app is to get users out of the app as soon as possible. For example, I have an app that helps me copy magnet links on my iPhone. I never spend more than two seconds in the app every time.