Google Content API for Shopping for non-merchants

Question

I've gone through entire Reference of Content API for Shopping (by Google): https://developers.google.com/shopping-content/reference/rest/v2.1 but I couldn't find resources anywhere for product prices, images, location, etc for non-merchants.

Is this API only to be used by Google Shopping merchants? If so, is there any third party where I can get Google Shopping data from? Thanks.