It has been suggested that DuckDuckGo doesn't report your "interest" to commercial retailers - can't comment.
Certainly if you search for a product on Google, then one is inundated with adverts from retailers of that product. Google is a commercial entity, therefore it is in their interest to sell your identity to those who think they can sell you something. n'est ce pas ?
Only saying, can't comment, I haven't sufficient experience of DDG, but have no complaints so far.