Opportunity - Products tab - Bill Status

The API currently does not show anywhere in the Opportunity or Products APIs if a product on a Won opportunity was billed or not.

I'd like to be able to build a gauge showing any products have not had an agreement set up for them yet.  This would help us ensure we're not missing anything on the billing side.

I had asked BG support to add this to a dataset but since it's not in the API, it's not available.