You can configure a retargeting email that has a list of products, that are not known at design time. They will be added from the payload at run time. For example, you can automatically send a cart abandonment email, listing all the products that were in the user's cart with an image, price, and link to each product.
The following videos explain the steps that are required to configure Product Listings in Transactional Emails feature.
Please note: This feature is currently referred to as Loop within the product.