From a Jira board, we can glean good information from the Backlog view when viewing an Epic in the Epics panel. We get a great progress bar and on-hover can reveal the percent complete for that epic and the number of story points earned (assuming you have your board's estimation statistic using story points).
When viewing the Epic issue in full-screen, we get a good progress bar that displays a green, blue, and gray fill regions based on the total number of issues in that epic that have been completed, in progress, or open (of course, based on your status and mappings). On-hover, it reveals the count of issues for each fill color.
These are both wonderful scales of performance. I can get total story points delivered from an Epic and its total issue count delivered.
But, how can I present this data on a Jira dashboard? I'm open to any Atlassian Add-On to achieve this, if needed. I see no such means to get this valuable data.