Hi -  You can do exactly this with the API functionality on https://apps.shopify.com/qr-code-designer.   Ping us if we can help you set it up! JP 

Create of QR Code Generator Hub here. We have a *lot* of Shopify merchants that use our app to do *exactly* what you described.  Our app also has many features to help with this exact use case (such as QR Code order attribution). Feel free to contact...

A lot of merchants use https://apps.shopify.com/qr-code-designer to do exactly this.  They create a QR Code that links to the checkout page for an entry fee for their event. You can even create a QR Code that acts as a ticket for the event (see this ...