Hi Mike,
Thank you for writing. I'll add this up as well as a feature request. Just to make sure that I am capturing your feature request correctly, are you specifically referring to URLs generated when one wants to share the link to an annotation, or are you referring to any URL that is found in an annotation card? If it is not too much to ask, can you provide a use-case where you think having the QR code will be very beneficial for you.
Best,
Janrae
Hypothesis Support