Google Cloud Platform (GCP) is a suite of products for webmasters, but do they offer payment gateway services as well?
Since you are storing and administering everything in their servers, it would make sense to also rely on them the secure payment, but I could not find information about GCP providing this service.
It does not appear that Google provides a payment gateway as part of their cloud platform.
I say this because they have an article about setting up a a PIC-DSS compliant environment using their services. That article only ever mentions an "external payment processor". If they offered their own payment service, they would surely mention it in an article about how to use them to securely accept credit card payments.