These apps will be nearly impossible to monetize. No ads, but also basically no in-app purchases either. I doubt many children will see a parental gate and actually do what it asks. They'll just treat it like a dead-end and close the app to find something else to play with. This category will be entirely populated by totally free apps that are created solely for branding purposes or funded by NGOs to push an agenda, with a very small number of apps created by uncompromised people who sincerely want to make the world a better place for children.