Vaulted cards and store credit are now supported in Checkout for buyers who have been authenticated with the Storefront API such as on headless storefront flows or mobile apps.
Append the customerAccessToken into the Buyer Identity object of the Storefront API Cart and buyers now have access to their vaulted cards or store credit if applicable. For security reasons and best practices, request the checkoutUrl when the buyer is ready to navigate to checkout, this can be re-requested if needed. This ensures secure authentication while maintaining a smooth payment experience.