I tried to set up a test call with a potential customer with vuforia chalk, and the chalk app kept crashing on his samsung galaxy note 20.
Also I've noticed that the live annotations where deactivated as default in the app. If this is the default, then you have to explain to every new user, how to turn it on before even starting the call.
"Supported Mobile Devices": https://support.ptc.com/help/vuforia/chalk_app_center/index.html#page/Vuforia_Chalk_Admin_Center%2Fc...
It is supported, but it the app crashes anyway.