I personally believe that product miniatures should NOT have rich content metadata. Especially when you display them on product page - for example if you have list of related products, "customer also bought", or "other products from this category". In this situation, google has hard time to understand what the page is about. From google's perspective, the product page contains multiple products. Sure, one of them is primary, but how should google know this?
The primary goal of google is to understand and interpret the page. Adding too much noise to the page is not helping this, I think. I strongly believe that, in this case, less is more.
I have it implemented like that on my website, and I'm very happy with it. I have zero warnings/errors in search console, and more importantly - my rich data are displayed correctly in search page result.