Firsts of all, I use a video mixing program called OBS Studio (available for Mac, Windows and Linux). It allows you to mix cameras, pictures and screen windows and present to the system a “virtual camera” that Zoom can use for it’s picture.
The inset picture is using an iPhone on a flexible holder clamped to my desk just out of sight at the bottom of the screen. Much more clear and more comfortable than holding the guitar higher so people can see my chords.
I love watching the chording hands as others play so that I can learn more, so this lets me easily practice what I preach!