For all reports built in report builder that are on a dashboard, you can click the 3-dot "more" menu to add those reports to Gainsight Home. However, I just added a Scorecard Widget to a dashbiard and I do not see that option in the menu.
According to ticket 326173 this is how Gainsight is intentionally designed and an enhancement request.
Please update the system so all items visbile to users on a dashboard can be added to Gainsight Home using the 3-dot menu.
#productparity!