I don’t remember if this worked but: disable Bluetooth, turn on hotspot on the phone and connect the watch to the hotspot, update from the watch.

Especially since you can already check it in the data logs on older phones.

https://www.igeeksblog.com/how-to-check-iphone-battery-charge-cycle-count/

And probably have a separate controller? I’m not very technical at all but I’d assume it’s much easier to fit a separate one on a large surface like the iPad has

Edit: google confirms the iPads have a separate USB3 controller

Or because the base iPhone 15 uses last year’s Pro chip which didn’t have a USB3 controller.

They said it couldn’t be done but it’s slowly finally happening, let’s go