> Keep in mind that once customers expect your app to follow the Kids Category requirements, it will need to continue to meet these guidelines in subsequent updates, even if you decide to deselect the category.
Sounds like they’re ready.
This seems more like an opt in choice for developers of the app as opposed to forcing apps to the kids section (which as you stated would be impossible to manage)
The screen time feature lets parents control kids iPhones/iPads through content ratings, I am sure it would be relatively easy to extend it to kids feature. Also kids Apple ID would have the age info.