Hi Rohan, So your requirement is, If you click on the list which is a PO, you want to see the view which you see in PO Fiori App in My Inbox detail view(may be whole detail screen or a tab which shows PO details), right?.
Extending whole of the Detail screen is currently not possible with any standard mechanisms as for as I know. If your requirement is adding a tab or using an existing tab to show PO related information, then you have to extend the My Inbox application. It might require you to provide extended service and using Fiori UI extension points. Please check My Inbox extension guide on what all you can achieve.
You might also develop a BSP Application to show PO details using SAPUI5 technologies and configure it as Task Execution UI in SWFVISU. This UI will open when you click on "Open Task" button in My Inbox. Please note "Open Task" button is visible only in Desktop.
Regards, Prashanth