Apple allow me to buy stuff with my apple account on other devices, apple music, iTunes, etc. So clearly if I'm giving them money they are just fine with non ap

Apple allow me to buy stuff with my apple account on other devices, apple music, iTunes, etc. So clearly if I'm giving them money they are just fine with non apple devices. All I want to do here is change thr screen time allowance on my kids phone. Its totally possible, and security is clearly not the reason if they allow 3rd party devices for financial transactions.