Lots of posts on everyone's unique method; I'll add mine.

I'm on Xfce (X) with three monitors. When I share I can pick just the right-most. Shares everything in that panel. Just need to be careful what is on 3. Then, I zoom in the app (browser, VCCode) for viewers.

But I like this idea of a virtual, so I don't accidentally leak a window I shouldn't.