You need a report or app where you can get complete list of purchase orders which are not yet released and at which level they stuck.
"Image/data in this document is from SAP internal systems, sample data, or demo systems. Any resemblance to real data is purely coincidental."
SAP S/4HANA Cloud
From Manage Purchase Orders app you can only extract the current status of the Purchase Order.
You can use the app Flexible Workflow Administration and check the workflow logs for each item as you can see in the image:
Also if you would like to create your own custom view to please check the following community post
Workflow log, Report, List, Purchase Order Workflow , KBA , MM-PUR-PO , Purchase Orders , BC-BMT-WFM-RUN , Runtime , Problem