PCI compliance on each platform?

Separate the provider's assessed service from your merchant obligations. Confirm current provider evidence, the payment flow, custom scripts and integrations, and how responsibility is divided. A hosted checkout can change the work you own, but it does not by itself establish which questionnaire applies to your business. For self-operated Magento, include the application and hosting responsibilities in the review. Ask your payment provider, acquirer or qualified assessor to confirm the appropriate scope.

Official references: PCI SSC merchant outsourcing responsibilities; Adobe PaaS responsibility model.