For Android: learn the hard reset combo for your phone, especially if you encrypt it.
After rebooting, pattern/PIN will be required to decrypt the phone. Biometrics won't work for this step. This is what graphene does for security, tries to keep the phone in a "before first unlock" state by rebooting on a timer. You can't even read anything over USB/ADB, it's scrambled until you unlock the phone.
The only drawback to just keeping your phone in this state is none of your apps are loaded, so no notifications/updates/processing at all.
You don't even need to do that. You can go to the power down menu on Android 14 and select lockdown. Even from the lock screen without unlocking the phone.