Yes, it’s hard to do the Zoom lesson. However, there is one great program that makes it easier to use two microphones while doing a lesson. Audio Hijack. I have a little complex setup that allows me to use the MacBook’s mic, but when the instrument mic kicks in, Audio Hijack “ducks” the MacBook’s mic down. Meaning it lowers the volume so you get the real mic not the crappy MacBook Mic.
Anyhow, Audio Hijack has been essential in teaching. I love it. Here is my setup.