• Google Customer Reviews is a free program that lets you collect feedback from your customers who’ve made a purchase on your Shopify Store. It is a kind of merchant ratings(Seller Ratings) service similar to the ones listed here. 
• This is not a program for Product Ratings and Reviews. For product reviews, there are many apps on the Shopify Apps store.  
• Ratings from Google Customer Reviews apply to your seller ratings eligibility.
• Seller ratings appear on Search Ads, in Google Shopping, and on an optional badge that can be displayed on your site.

An example of Google Customer Badge: 

Must Read About the Program and the App:

• Our app just provides technical Integration and lets you show Opt-in form on Desktop and Laptop devices. After Opt-in Pop-up is shown, app’s role is over.
• It is up to your customers if they want to opt for Google’s Customer Reviews’ Survey requests or not.  
• Google Customer Reviews is a merchant ratings program. Product reviews collected by your stores using any other Shopify app are not considered for the program. Unfortunately, we have no control over this policy of Google, so we can not help you include your product reviews.