This in turn leads to an interesting effect, where the useful life of an Android device can actually be longer than that of an iOS device, despite the latter having access to OS updates for a longer time.

This is so true.

I have a first-Gen iPad Air that runs fine, but is fast becoming useless, despite having received an OS update months ago.

While an old Galaxy S4 I have around runs many apps that still function fine (especially since I can find old compatible versions on apk mirror).

Pretty frustrating, because the iPad Air performance is plenty for the things I want to use it for.