In 2024, Apple announced that as of September, it would only allow gambling apps native to iOS to be hosted in its App Store. This change was due to the fact that many gambling apps were 'container' apps, as they essentially repackaged their websites into apps, which was easier for developers to maintain.
Installing an APK on an iOS device is impossible as both platforms are incompatible. But if you are keen to install APK on iPhone, you can go for either of the options: use jailbreaking process or an APK version of the file, which is specially designed for iOS.