No, I completely understood, and my first comment explains what you need to do allow a user to scan a QR code, open a form, and pass those hidden values through the form. The difference is the extra step of pressing a button to open the form once the page loads, but that could probably be replaced with a form container instead directly on the screen, so the user would be taken directly to a form without having to click a button. Pulling the values from the url would still be the same.
This has been done before and from what I hear it works very well.