You are going to spend a lot of time and money to address this. Better solution is to buy a second Chromebook only for school or personal use snd explain to your kid that their government hates them.
Better yet, ask the school to provide a Chromebook if they want to spy on and control it. The owner should have the ultimate authority on what the device does - so the school should spend money for the power they demand.
My solution is a pragmatic one, yours is a dead-end most likely, the point was to paper over the issue and move on unless OP wants to spend a lot of time and money on lawyers fighting it.