Paypal used to offer chained payments where the marketplace took a commission and the buyer and seller were all third parties. Can you do sg like this with Google Pay? Their FAQ at https://developers.google.com/pay/api/faq implies that an e-commerce platform can do this with a hosted checkout page. Any more info anywhere?
Google Pay itself doesn't actually execute the payment, it returns a payment credential which you can then use to execute a payment with a payment service provider. That said, the Google Pay payment credential can be used in a marketplace use case, but will only be involved in the first part of the transaction. That is, between the user and the merchant of record (the marketplace). The dispersement of funds between the marketplace and the third party would take place independently of Google Pay.