To start with, I upgrade my SAP_UI component from version 750 SPS07 to version 751 SPS01 to unlock SAPUI5 version 1.44.13. For this I chose Install or Maintain an Add-on in SAP Maintenance Planner and select FRONT-END SERVER 3.0:
This results in a warning that SAP_UI version 751 SPS02 which I would require to reach an equivalence level is not available yet, but since I am working on a sandbox system, I ignore this for now and address the issue once this patch becomes available around mid-May, according to SAP Schedules for Maintenance Deliveries:
Later in the upgrade, I have to actively ignore this warning again:
With this I configure my SAP Easy Access Menu for Fiori Launchpad according to the SAP Help and add the Create Purchase Requisition app to my Buyer (MM) group:
As a result, I can Create a Purchase Requisition from my Fiori Launchpad:
To be further processed with the standard Fiori Order from Requisions app:
For me, this closes the loop to run my procure to pay process entirely from the Fiori Launchpad. Well done SAP ;).