In the workplace you have BYOD, bring your own device. But in order to access the services needed at your workplace, you need to install MS Intune and similar, which basically give your workplace limited admin access, they can remotely wipe your device, set stronger pin requirements etc. Perhaps something similar should be made available for schools. So the school can limit use of the phone without putting the phone in a drawer
Depends on the enrollment type. If they are using app protection policies they're just wiping the corporate data from apps. If they're making you completely enroll your phone they could wipe everything but that's a no go for most people.
