Selling this data isn't possible for a normal website.

The reason Facebook and Google did it is because you're basically permanently signed into both on mobile devices, and their apps provide sufficient information to identify *all* of your devices and join it into a single identifier.

This is known as cross-device matching. And Amazon have that capability. And Amazon are behind in the search-tech market quite a lot.

So their offering has to be better, but also probably won't beat it by tech offerings alone.