Develop a new payment gateway for shopify POS

[BenJost]

Hi, we have a developed a QR code based payment gateway and now want to integrate with Shopify.

The desired experience:

• merchants requests "pay with X" within the Shopify POS
• X displays QR code on a device (no physical connection to Shopify POS)
• user scans QR code and pays via X
• X sends "Payment successful" back to Shopify POS 

Can someone guide us to the right developer doc to create such experience (we only need the transaction_ID, amount, currency from Shopify's API)?

Thanks in advance.

Ben

[N_Abey]

Dear @BenJost 

First of all to integrate a payment Gateway to Shopify you must have access to Shopify Payment  SDK. as per my knowledge Shopify stoped providing this access to third parties for some time now.