Show Product Stars in Google Shopping

I run my store on Shopify and have already gathered a solid set of product reviews outside of any app. What I now need is for those reviews to power the star ratings that appear beside my items in Google Shopping ads.

The job is to take the reviews I have, transform them into a Google-compliant Product Ratings feed, upload it to my Merchant Center, and make sure Google approves everything so the stars start showing. If mapping GTINs, SKUs, or Shopify product IDs is required, please handle that as part of the feed build. I’m happy to supply the raw review data in whatever format you prefer.

Deliverables
• Google Product Ratings feed created from my existing reviews
• Feed successfully submitted and approved in Merchant Center
• Stars visible in live Shopping ads (or clear evidence from the Diagnostics tab)
• A brief set of steps I can follow to add new reviews in future

Feel free to use whatever workflow, scripts, or review-import tools you like—just keep the process efficient and fully compliant with Google’s policies.