At the moment, it's possible to sync the payment cards you have in Google Pay with Chrome's autofill feature. This is incredibly handy for when you make purchases online, especially on sites that don't have Google Pay as a payment option. Unfortunately, it's not possible to sync your data the other way, from Chrome to Pay, but it looks like that functionality will be added in the near future.
According to a commit in the Chromium Gerrit, discovered by XDA Developers, an "intermediate bubble UI for local card migration flow" is being planned. This sounds slightly cryptic but is further explained as a way "to offer users an option to upload chrome local credit cards to Google Pay server" with the bubble being the start point for that process.
Chrome's autofill has long been used for helping us input all kinds of form data, so if you're like me you have all of your relevant cards in it. While I also have those in Google Pay now, it would no doubt be beneficial for newer users to get an easier way to migrate credit and debit card data — it just makes sense for it to go both ways.
- Chromium Gerrit
- XDA Developers