This is not true at all districts.
In my current district all other engines are blocked. My daughter has permission to use her phone to utilize Kagi from her teachers, but she cannot use it on the school devices.
I wonder if this is actually an opportunity for Kagi by having some kind of education pricing for schools specifically for this reason.
Yeah, you have to be real careful. Our son has his own Chromebook and he once logged into it with his school account to do something. It installed the district's certificates and other blocks so that even his personal account couldn't do anything. We had to factory reset the machine.
So it's the schools that're making kids - and thus the next generation - dependent on Google.
I've recently learned my daughter, with teacher permission, regularly has to use her phone (in her otherwise phone-free school) to get around blocks on basic stuff. Like in her math class the teacher regularly has them review techniques using YouTube videos (from an approved channel), but YouTube gets blocked every so often. Why? Very possibly no one knows. So she'll be sent to the front office where they can unlock her phone and she can use it to keep doing her work. It also came up recently when she was researching drug addiction for a paper, and all related search terms were banned.