The oldest supported device for iOS16 is the iPhone8 (2017). If you have a device without iOS 16, you must have iOS15 or even older. The oldest device supporting iOS15 is the iPhone6 (2014). That is 9 years old.
I feel your pain. But then again, it is amazing how you apparently still rocking a device that is nearly a decade old and is still acceptable fast for you to use. That in itself is a amazing thing. If you still want to use your older iPhone, you sure can (even without getting newer iOS updates) and you could still use matrix from the web. You do not need to use it via an App - even tho understand how it would make it more convenient. But it still blows my mind what lifetime you were able to pull out of your device. And maybe even will continue to. Kudos.
Why does he have an iPhone 11 and can not update? I have a XS and still receive updates (of course) and currently are on 16.5.1. The 11 is sure not falling out of the update cycle just yet. In this apple site the 11 is of course also mentioned for iOS17.
I do not get why he has an 11 without getting updates. What does the update screen show? You telling me his 11 is on 16.3 and the dialogue says “You are on the latest”?