"extremely reduced security"

That's such a fun statement.

Any security measures taken always remove agency from one person and give it to another.

iOS takes my control away, and in turn gives that control to Apple. GrapheneOS takes my control away and gives that to the GrapheneOS developers.

The "security" you're talking about doesn't prevent certain data from being accessed, it just changes who controls the access.

If the user cannot be trusted with their own data, then there is no solution anyway. They'll just tell their private data to a scammer on the phone instead.

There is no solution against a user that wants to give their own data away, but if you try to prevent that, the only thing you'll accomplish is destroying general purpose computing.