I’m going to be the jerk and just say “use a real camera”.
Don’t get me wrong, I love the iPhone, and even as a photographer I use it more than anything else. But moon pictures require a zoom lens. Otherwise you’re just not going to get it right. 200mm focal length plus, and the iPhone 15 pro max’s 5x zoom is only 120mm.
That, and a larger sensor for better low light performance.
Don’t use an app. Use a pi-hole. Block the entire house with granular control over what gets through and doesn’t!