How to use Apple account balance as a payment method
My friend can use his Apple account balance to pay for gas at the pump
Question marked as
No he cannot. He is mistaken and so are you. Your Apple account balance can only be used to purchase Apple products and services. Your friend may be using his Apple Card credit card or his Apple Cash debit card but not his Apple account balance. Not possible and never has been.
Apple Gift cards cannot be used as founding sources for payments other than Apple products and services either.