using a virtual screen (spaces in Mac) as 2nd display for output

as we are now operating from home, would be useful to have the ability to run the 2nd display to share screen or stream, etc without the need for a physical 2nd monitor as that prohibits a rotation of volunteers. thank you!

Use Space Desk in Windows/Android. This will help you to use your phone/tablet as an additional monitor

How do we do this on a Mac?

You can now create a virtual screen in Presenter, select "Window" for the display when creating the screen under Screen Configuration.