Give me a break. A screen swap in a modern smartphone is not something you can do in a bar in the time it takes somebody to go the bathroom. You need tools like a heat gun to even get the things open which greatly greatly limits the scenarios where and when something like this could occur.
Yeah, sure. Let me put millions to compromise a supply chain and get access to what thousands of people are sending on their WhatsApp accounts /s.
There is a reason why any type of security analysis needs to depend on your treat model. Unless the target is worth it, it doesn't make sense to do what you described.
Instead, millions of people lose a option of doing their screen repairs for cheap. And of course, Apple will have access to more money as always. But sure, security...
What are you on about? All you'd need to do is find the place where your target is going and either bribe the teenager behind the counter or, depending on the value of the target, compromise the distributor from wherever the parts are coming. This is neither expensive nor difficult to do.