This is the only reference I could find on the web listing URL based PSPs adhering to the the PaymentRequest API. Does anyone have a more recent or comprehensive one? This is the list in that link: -
Existing payment method identifiers Google Pay (https://google.com/pay) Apple Pay (https://apple.com/apple-pay) Samsung Pay (https://spay.samsung.com)
I also believe Alipay suports the Payment Request API. How/Where do I find out who currently supports it?
I would assume that list is a ~complete list, based on the information in the page.