Hi,
as i´m searching at the moment for solutions within this topic i´v seen your post. As far as i´ve learned you need this API to getting this id:
https://legacydocs.hubspot.com/docs/methods/products/get_product_by_id
This id is not shown in the product library and cannot be exported.
Question: Do you have a solution for your purpose in the meantime (adding products to deals via API)?
Best Regards