This idea that protecting users is worth the cost of giving up your ownership rights is fallacious.
Protecting 1 million grannies is an entirely different risk class than the security implications of stopping everyone from using their devices as they see fit.
Protecting 1 million grannies means everyone loses ability to install apps that:
-allow encrypted chat
-allow use of privacy respecting software
-download art/games/entertainment that is deemed inappropriate to unelected parties
-use software to organize protests and track agents of hostile governments
-download software that opposes monopolistic holds of controlling parties
Using Linux is also not a real choice. To access my bank and health services in my country, I require a mobile device that is remote attested by either Apple or Google which are American countries. Hell, it's becoming closer to reality that playing online video games requires remote attestation either to "prevent" cheating or for age verification.
Thus the risk widens to the sovereign control a nation has over its own services. A US president could attempt to force Google and Apple to shutoff citizen access of banks and health services of an entire nation. Merely the threat could give them leverage in any sort of negotiations they might be in. For some nations in the future, the controlling nation may be China I imagine.
I think the real regulatory solution here is to break up monopoly practices. While the EU's DMA is all well and good in some ways, the EU is also pushing Chat Control... In a more fragmented market it becomes impossible for a bank or health service to mandate specific devices for access (they lose potential customers) so you could theoretically move to a device that doesn't do draconian style remote attestation that breaks if you go off the ranch. We need more surgically precise regulatory tools than sweeping legislation that would keep using alternatives like Linux or FreeBSD or whatever actually viable. It also makes it much harder for that same legislative body to enforce insane ideas like Chat Control.
The answer is not protect users from themselves. The answer is more freedom, with a legal framework that helps all users have more choices while helping victims acquire restitution.