Thank you for your suggestion for DragonByte eCommerce. Your request will be reviewed by a member of our team shortly.
Unless there are any problems preventing these features from being added to the product, this thread will not receive another reply until it is time to review logged feature requests for implementation.
We appreciate you taking the time to help us improve our products!
Those are optional fields, certain fields like priceValidUntil has no value for these products.
Also, some of those fields do exist, if it makes sense for them to be added. For instance, the rating fields are added if the product has ratings.
That being said, apparently Google violates the spec by not allowing text in the "price" column, so free products currently cause an error. I'll resolve that and look at whether there's any more fields from that list it makes sense to add.