Why is the "PREVIEW" button shown in products structured data?

Question

After I implemented JSON-LD format for products on my website, I could see the following preview button on Google Structured Data Testing Tool:

I hope Google has implemented Rich Cards for just Articles, Recipes and Video till now. Does it mean that Rich cards for Products are on the way? Note: The products structured data is shown in Google Search Console and has no errors.

Answer 1

Google offers a product rich result for Google Search and for Google Images.

It makes use of Schema.org’s Product and Offer/AggregateOffer (and, optionally, AggregateRating and Review) types.