Ancedotal: I used to believe in this "freedom to install". Than my Father got scammed (~$1000) in the name of Electricity recharge. The APK was sent over WhatsApp. Now I am not so sure how to implement this freedom. At the bare minimum there has to be big red warnings. One thing which can immediately improve security is forbidding SMS read access forever. Just like Apple does. No App should be able to read SMS.
Our right to choose install software on our own devices should not be encroached because over-trusting elderly follower scammers instructions.
We can protect people like your dad with an opt-in system like parental controls. Have a responsible family member lock the system down however you deem fit.