Using the Shopify Shopping apps' metatags
Using the Shopify Shopping apps' metatags

Using Paginate=1000 to maximize number of products returned
Adding variant.barcode as gtin
Using the meta tags generated by Shopify's shopping app to power Age_Group, Gender, and Google_Product_Category
(Thanks to https://github.com/samthaman for the work & code!)
Czarto/ShopifyScripts