ApplePayGateway
Apple Pay, through PassKit directly — there is no Apple Pay SDK to depend on, PKPaymentRequest and PKPaymentAuthorizationController are the integration.
Apple Pay does not settle money. It returns an encrypted WalletToken that a PSP with the matching payment-processing certificate decrypts and charges, which is why this sits behind the same prepare/pay split as every card gateway: the backend still creates the order, and a client-side success here is still only a hint.
Ships GatewayStatus.KYC_GATED and reports WalletAvailability.NOT_CONFIGURED until a real merchant.* identifier replaces APPLE_MERCHANT_ID_SENTINEL. A merchant id needs an Apple Developer Program membership, so there is no solo-runnable sandbox to pretend otherwise about.
docs: https://developer.apple.com/documentation/passkit/pkpaymentauthorizationcontroller