As UnoriginalGuy says: first big issue will be supporting 50+ devices * browsers on said-devices (that alone should tell you to avoid it)
Then you'll need to analyze and build up a collection of thousands of e-commerce stores with their specific check-out implementations.
Then you'll need to create filters for sensitive products (and try to define what is sensitive to who)
Then you'll need to support angry spouses who bomb your limited support email due to revenge-restrictions, partner-trolling, etc.
Lastly, some Google AdSense will become counter-productive to making money from this (if you intend to).
Ads sell products and you stopping product-buying would be, well...
I own multiple devices (smartphones, PCs, and tablets) you could never be on all of them and I could bypass your restrictions.
Plus I have three+ browsers installed and am familiar with safe mode and incognito mode.
Have you tested how much people in your circles needs it?