I don't think it's an issue on iOS, Apple is able and willing to update old devices if needs be. My 5S still receives the odd security update in iOS 12 from tim

I don't think it's an issue on iOS, Apple is able and willing to update old devices if needs be. My 5S still receives the odd security update in iOS 12 from time to time (basically when something really big comes up). If it would make sense, I'm pretty sure Apple could update the first iPhone still. And that would cover every iPhone 1 in existence. Android with its fragmentation makes that pretty much impossible.