Management Dashboards for Projects

I have a frequent request to collate the data from many project websites into a dashboard summary for managers.

Can I use Dashboard Designer to interrogate OOTB SharePoint Online project template websites (multiple) and generate a summary.

Something that shows the typical high level overview of all project sites in the site collection.

Has anybody created something like this?

Sure, you can implement this functionality with the help of Dashboard Designer. A very similar case is described in our blog: