It's not the shape of the API payload that is the problem, is it? Few banks have a REST API for payments is the issue IMO.
This is different from an API schema of a /payments/ endpoint being segregated from the actual resource that is being paid for.
In this model, the payment is the cost of entry for the resource request itself. It's not as directly applicable to all payment scenarios, but enables a new class of transaction that is effectively pay-per-request.
It's worth noting that this protocol is primarily supported by Coinbase today -- You'd be using USDC on the Base network (Layer 2 on top of Ethereum). However, the protocol itself is opening meaning anyone can self-host the same mechanics on any network, with any token/crypto asset.
I support one of the similar projects in my organisation and I can't wait for golive.