This is my concern too. We already have quite sophisticated scams guiding people to install TeamViewer, AnyDesk, etc on PC’s; you can bet they’ll adapt their techniques to work on iPhones too, guiding grandpa through side loading malicious software.

Hopefully iOS will make a distinction between side loaded and AppStore loaded apps and adjust permissions accordingly (via a VM, container, or some other mechanism).

Obviously not perfect, but security is a never ending game of cat and mouse.