All these different groups your speaking of are called
personas. Apple should have each of their personas identified based off their technical prowess, their life experiences, health, how they connect for user updates and whatever else may differentiate a group of users from one another and needs to be considered and accounted for.
Once you have that you create a user journey map for each of those personas - in this case they need a user journey map for updating. Your test teams then have to take each persona and run through testing with those constraints and capabilities in mind.
They don't have a high-speed network or are using a cellular network? One or more personas should have accounted for that. Color blind? One or more personas should have accounted for that and there's software available that can make your screen as it appears to those who are colorblind.
These personas should be corporate-wide - these are your customers after all. I would be shocked if Apple isn't doing something like this, but then again, after getting a glimpse at how the sausage is made I've come to the conclusion Big Tech isn't any better at creating and testing software (well, not that much better) than anyone else.