Is it permissible to eat products that contain the substance "Diglycerides" in America, given that its source (animal or plant) is not mentioned on the product, and with the possibility that its animal source could be from pork?

The basic principle regarding things is permissibility until proof of prohibition is established. Therefore, there is no harm in consuming what contains the mentioned substance, unless it is proven that it is derived from a forbidden animal, such as a pig, or from a permissible animal that was not slaughtered according to Islamic law, or if this is highly probable.