[w3c/payment-request] Extract actionable items from Shopify study (#772)

The [Shopify study](https://shopifyengineering.myshopify.com/blogs/engineering/shaping-the-future-of-payments-in-the-browser ) contains at lot of actionable things for V2 (e.g., it's pretty clear we need to solve coupons, better merchant/sheet integration, etc.). 

It would be nice to go through the study with a fine-tooth comb and extract whatever actionable items we can. We have some of these already (e.g., coupon codes is #145), but there might be others we haven't filed bugs for. 

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/payment-request/issues/772