Many music teachers are doing online lessons now, mostly via Zoom.
It seems that Zoom is the only popular videoconferencing software these days that allows you to disable all the postprocessing on the audio signal (echo cancellation, noise reduction, etc) through advanced settings. This postprocessing is very useful for /conversation/ meetings among many people with bad audio setups, but for two musicians and music signals, the postprocessing is highly detrimental, causing strange audio artifacts and causing instruments to drop out sporadically.
(It seems like there would be a market for videoconferencing software optimized for musicians, where the audio signal is sent at higher quality, given higher priority, and not postprocessed in detrimental ways. And without all the privacy concerns.)