Schools even have Cellebrite devices now, that is how prolific they have become. GrapheneOS has a duress password to wipe the phone and you can block all data or even power to the USB port while the phone is running. If you blocked all power to the USB port while the phone is on the only way to charge it is if it is fully turned off putting your encrypted data at rest. You can just disable data on the USB port options menu in GrapheneOS if you don’t want to completely turn off the whole port.
You probably already know this stuff I was just mentioning it for people reading this comment section. :)
The legacy SafetyNet check bypass may not be around much longer especially because hardware based attestation will be gradually replacing it.
https://grapheneos.social/@GrapheneOS/111504057847795464
Below is a guide for app developers who want to support third party OSs in a way that does not rely on Google. Most apps work on GrapheneOS just fine already but there are some banking apps and NFC payment systems that do not.
https://grapheneos.org/articles/attestation-compatibility-guide