shopify schema markup for product.It will be add in product.liquid or product-template.liquid file(Based on theme).It will be added underneath of product-template.liquid file. And also tested by Goolgle structered data testing tool. There are two warning shown up when tested,But they are not a major matter.Google takes time to verify those warning and also resolved by itself. The warnings are
priceValidUntil : if there are available info in product page,then it will automatically remove.
review : It can be resolve. You can find more at https://schema.org/AggregateRating