If you knew anything about payment systems, you'd know you get a nonce or receiptID and it is a front-end only thing. You don't do the backend banking yourself.

Maybe your backend sends an email, or saves the receipt, but that's peripheral.

The entire Payments flow is front-end capture, then the service doing all the actual backend payment part. It's a black box from your end and you can decide to do it entirely front-end if you wanted. There's no way around it.