The Payment Provider Gateway documentation uses the Magento 2.3.x version of the Braintree module as a reference application. The Braintree module was removed in Magento 2.4.0. The concepts described in this guide are still applicable to Magento 2.4.0, but the code samples are not supported.
Payment provider gateway structure
The following diagram shows the basic components of the Magento payment provider gateway:
The interaction between the payment gateway components looks like following:
Each component from this scheme is described in the corresponding topic: