I'll tell what i have been thinking a while ago.
But i never tried it out because i didn't have an opportunity.
On the Schok Classic Phone there was about a half a year ago a System Update.
After the Update there was a Lock Control 2.0 in the settings.
And there they had an option to block to reset the phone or to install apk files and to disable apps.
So what i would say is, to check (the easiest way would be with adb control because there you could see very good each app ) if there is installed a app that is possible to be extracted and used on another phone.
Let me know what you think about it, i think that it could help the whole "flipphone community"
Jklein It would solve your problem too!