Uploader code on Product pages

I'd like to add an image upload to the product form when you hit add to cart. I have tried to implement squarewebsites uploader but it only allows 10Mb and dev won't open it up more. I cannot seem to find an option that integrates in the same way with having the form pop up after adding product to cart. I am now trying to utilize Jotform but I cannot find a way to get it working with product form. I think Squarespace needs to have an option for an upload to a cloud service like google or dropbox for the commerce plan, having to utilize a third party for a form to get an upload button puts customer data at risk.  

I run a print shop. I sell my own merch and also custom printing like business cards and stuff. I'd like to be able to include an uploader of my product pages either BEFORE adding the item to cart, or if it's possible, redirecting to the 'upload' page AFTER hitting the add to cart button on those products. 

I'm currently using the same upload/form solution that everyone else is... custom form, blah, blah, and then using File Request Pro. But, I found a new option that works much more cleanly for me - Tally.so

Anyway, I have embedded a form on my upload page:
https://www.brownleepress.com/upload

I'd like keep that upload page as-is, then find a more user friendly/intuitive way to get there. A workflow that feels more natural. Now that I'm writing this out, I really like the idea of redirecting to an upload page after the add to cart button is pressed. The only caviott there is that I ONLY want it to move to the upload prompts for custom print items. Maybe I could use a special tag, or put the items in a 'separate' store?