Hi,
All the standard reports will consider the delivery completion at item level only. As of my knowledge, there is no standard reports which will show the consolidated header level status. Either you may download from ME2N and consolidate the status in excel - (pivot table or similar method) or you may go for a custom report.
If you are going for development, you may use the FM: BAPI_PO_GETDETAIL and get the GR details from the structure PO_ITEM_HISTORY_TOTALS.
Regards,
AKPT