I found the field "Starting quantity" In the report "Percent of inventory sold report" (sold quantity / starting quantity).
Where do I find it via GraphiQL?
I do found the current quantity by product variant (product -> variants -> inventoryQuantity)
but can't found the starting quantity field.
Found this solution https://community.shopify.com/c/Shopify-APIs-SDKs/How-to-display-how-many-have-been-sold/m-p/151202/... of setting metafield - but it not good for me, because, if I understand right, for each new inventory product you should set this field to the product - but I have only read access and have no control of define products fields.
I think that if this field is in an official Shopify report - it should be easy to be fetched via API.