In the UK, "GoHenry" is an app that is targeted at parents as a way to give your kids pocket money, and comes with a debit card option. Their target age range is 6-18.

Revolut also offers accounts from age 6.

Parents would get notifications, but I suspect most parents won't be technically inclined enough to have an issue with a well argued child pointing out they need that VPN to access a game server or region locked content that their parents don't object to.

That said, I'd suspect most kids looking to circumvent these blocks will just install a free VPN.