The apps that you are describing (free to download as well as use, and not even serving any ads) do not make any money. The focus for such apps is long term.
Are they actually without ads or just showing free games and find out there are ads but have to get paid version without ads? Every time i look for a free app.
Those advertisements will sometimes collect data on your children." Looking for Here are 20 free apps without in- app purchases. Breathe, Think, Do Elgersma.