If both, your product feed and your product reviews feed are set up correctly, you should be able to see your product reviews on Google Shopping.
Since the appearance of Google Shopping changes based on your location, please find the screenshots below for reference. The flow describes the search process in Google Shopping from a customer perspective.
Search on Google Shopping
User types search term for the desired product in Google Shopping, here:
Cold Massage Roller
Product Quick View
The Product Quick View already shows information such as product reviews and price.
Product Detail View
Available information from the product feed is shown inside Google Shopping. Also, available stores are listed.
Product Reviews (part of Detail View)
Google Shopping aggregates all available product reviews. Product review details on Google Shopping
Product Page (Shopify)
Shop button leads to the Shop's product page
Shopify product page