Stalkerware does exist on the App Store. The specific things that are possible differ on each platform (for example, getting access to calls and texts is a lot more involved on iOS and most apps will just let you unlock the device and access it directly instead) but there is plenty of potential for abuse on both platforms. In many ways the model is better on iOS with regards to these kinds of things, but we regularly deal with victims that are in situations where there does not exist a platform that I am aware of that can effectively stop stalkerware completely.