You can show the percentage complete on the roadmap, but this is based on total story points/ finished story points. Since this changes over time (new work emerge which is not detailed to stories yet, let alone estimated on story points)
We can roughly estimate which capabilities will be needed for the epics to complete, hence it would be good to show that percentage of complete (finished capabilities/ total capabilities)
When you click on an epic in the roadmap, you get this percentage in the new window. So it is visible somewhere.
Would it be possible to show this percentage on the green bar itself?