u/tiredsongtiredradio, our oldest iphone in our household is an iPhone 3G. That is the second iPhone device ever released by apple.
On that particular device (our iphone 3G) we have never replaced it’s battery, which it is severely degraded, so a charge lasts maybe 3 days max.
We use that device at home as a glorified remote control for our media center home theater system and as a media player.
Outside of iphones, we have 1st Gen ipod(s) as well and those, just like the iphone 3G, are all still working today (still with their original hardware, indlucing battery as well)
How long will they last?.. can’t tell you as they are still going strong todate.
u/TillAny4068, iOS, the operating system on all iPhones, is a closed developed OS by apple.
Any third party software out there, MUST use, in one way or another, apples drivers, whether they like it or not, to access the device.
Therefor, whehter you use itunes to make a backup of your device or a third party app, you are still using the same drivers, thus making the same api calls.