The goal is to be able to run a workflow where reporting is done while at the same time (and with the same user) display a portal page.

Either:
Run the workflow embedded in a portlet. Allowing the user to still see the rest of the portal page while typing inputs and executing the workflow.

Or:
A functionality to "start a workflow in a new browser tab", hence allowing the user to split screen and see/display the portal while at the same time running a workflow in the other window.