Sure. You ship the device in open mode, and then doing it is easy. The device supports closed mode (i.e. whatever the currently configured package installation sources are, you can no longer add more), and if you put the device in closed mode, getting it back out requires attaching a debugger to the USB port, a big scary message and confirmation on the phone screen itself, and a full device wipe.
Then you put grandma's device in closed mode and explicitly tell her never to do the scary thing that takes it back out again and call you immediately if anyone asks her to. Or, for someone who is not competent to follow that simple instruction (e.g. small children or senile adults), you make the factory reset require a password and then don't give it to them.
Make it an obscure option in the first time setup so all the users that click next next next will end up with the secure mode, while the open mode requires fiddling.
This isn’t a gdpr opt out where both alternatives need to be equally easy. We (as a society) absolutely need the devices to default to the current model when purchased.
Very nice!
I’m sure I’m missing a problem with the following approach: shipping in _closed_ mode with a sticker on the front notifying the person they should do a factory reset immediately to make sure they can do everything they want to do. During the reset, include a scary message for those who opt in to get to open mode.
Everyone simply goes by defaults so it would only be technical people presumably who would even get into the open mode in the first place. And then require the debugger to leave closed mode like you said.
Edit: this comment worries about solo/asocial/“orphaned” members of our society