No matter which integration's dashboard you're browsing, you can easily add any widget to your custom dashboard.

Hover your mouse over the widget.

Then click the ellipsis ("...") at the top right, and choose "Add To Dashboard".

If you have more than one custom dashboard in your campaign, you'll be prompted to select the exact custom dashboard to send the widget to.

Your widget will be copied to the custom dashboard. To avoid displacing any other widgets there, the new widget will always be added to the bottom of the dashboard.