Thinking about Alternative Payments using QR codes in Face-to-Face Transactions?

If you are looking to achieve Alternative Payments Processing using QR codes for the "Card Present" environment, or should we say 'Face-to-Face' for these attended / unattended physical Point Of Sale -

Here are two high-level, non-technical (non-UML), Sequence Diagrams -

Which will demonstrate the main two flows you must be familiar with:

Merchant QR and Consumer QR

Bonus: Some Pros and Cons regarding each of the flows below

Merchant QR Flow

Consumer QR Flow

Merchant QR is a more clear, straightforward and easy to implement on both sides, meaning for the Wallet (serves the consumers), as well as for Payment Service Providers (who serves the merchants). This brings faster Time To Market, less maintenance, less troubleshooting and high level of service availability.

Consumer QR is more complex both for the integration phase and for day to day maintenance and operations

Consumer QR provides a great benefit already in use by some of the largest, most famous Wallets - it suites underground / no cellular network locations, the phone generates secure tokens with the server when online; going offline it may use such tokens when rendering the QR and it is up to the terminal to have internet connection to process the flow. In this case the Wallet's servers will validate that the token is real and legit and steps 6 and 7 in the diagram becomes non-mandatory (transaction is approved, and the consumer is charged by displaying the QR to the terminal)

Merchant QR in terminals offering multiple payment options, cannot always display the same QR code, therefore some extra interaction is necessary, or a more complex integration for Unified QR Solutions

Consumer QR requires a camera integrated to the terminal or ECR, therefore it will not fit some of the existing solutions in the market; It is also a bit more complex on the UX, the consumer must present their mobile phone to the camera correctly; in

Merchant QR most consumers will find it more intuitive to scan on their phone; they do not need to interact with the terminal's camera...