In RepU, open your widget, choose light or dark and left or right, then click Copy next to the embed snippet.
Open gatsby-ssr.js in your project root, or create it. In onRenderBody, use setPostBodyComponents to add a script element with your src and data-repu attribute.
Need more detail? See the official Gatsby guide.
Rebuild your site and deploy it, then open your live site to see your Google reviews.
Check your live site in a private window, not the editor or preview. A domain-locked widget only shows on your own domain.
Gatsby changes pages without a full reload, so check by reloading the page. Make sure you rebuilt after editing gatsby-ssr.js.