This is a great idea. I was wondering how could teachers draw on their iPad and show it on their laptop.

I just gave it a try on my iPad 7th gen and my MacBook (running macOS Catalina) and it worked great.

One thing to keep in mind though, when I connected my iPad to my mac via sidecar, many of the menu bar apps got hidden due to lack of space on my menu bar. So, I had to start the "Annotate Screen" via keyboard shortcut.