Visa Direct would be a good fit for your QR code use case. Here's the link to the Visa Direct documentation - https://developer.visa.com/capabilities/visa_direct/docs
Please see additional Visa Direct API information by navigating to the link below for information on QR code.
How to Use Visa Direct > Using Mobile Push Payment API - https://developer.visa.com/capabilities/visa_direct/docs-how-to#section4
Also, the Visa Developer Program, offers contactless payments. If you're interested in learning more about contactless payments, please refer to Visa Token Services APIs and Visa Chip Simulation Service APIs.
Visa Token Services might be a good fit for a requirement of taking contactless card payments via a mobile device. We have Card-On-File" (COF) functionality available on the Portal and these are the APIs that enable provisioning and use of tokens for HCE-based contactless (NFC) payments and for in-app purchases using tokens provisioned to a mobile device.
Additionally, Visa Chip Simulation Service enables simulation of contact and contactless transactions based on Visa chip standards, and may serve as a test simulation for chip and mobile transaction applications.
Here's the link to Visa Token Service - https://developer.visa.com/capabilities/vts/docs
Here's the link to Visa Chip Simulation Service - https://developer.visa.com/capabilities/vsdc/docs
Please navigate to the below link for information on the Tap to Phone program:
If you have any questions on Tap to Phone, please contact firstname.lastname@example.org