Hi @CRoach5 - apologies on the delay here. You can actually pass through email address to a payment link by adding a query parameter to the end of the link. For example:
https://app.hubspot.com/payments/xyz?referrer=PAYMENT_LINK&email=name@domain.com will pass name@domain.com to the checkout page. The buyer can still edit it if they wish -- it’s a good idea that we make this uneditable, I’ll pass it along to my team.