To integrate with Google Pay it is possible to send 'google' in DS_MERCHANT_PAYMENT_METHODS
To integrate with Apple Pay it is possible to send 'xpay in DS_MERCHANT_PAYMENT_METHODS. This method will also show Google Pay.
In the library, it is only needed to update the getAvailablePaymentMethods method so that these methods are available in dependent libraries (for example, commerce_sermepa module).
Redsys allows integrating with both Goole Pay and Apple PAy:
https://pagosonline.redsys.es/googlePay.html https://pagosonline.redsys.es/applePay.html
In short:
In the library, it is only needed to update the
getAvailablePaymentMethods
method so that these methods are available in dependent libraries (for example, commerce_sermepa module).