The iPhone 14 battery is considered user serviceable (but not the pro), the iPhone 15 pro has now adopted the 14's design. Basically the rear panel is now straightforward to remove, when before one had to go in through the front.

> how hard it is to replace the iphone battery

its like 30 minute job, maybe less for pros

p.s. if you don't like the feature - don't use it!

I assumed it was meant for occasional use by people on the go (like on an airplane without a charging port) who need to charge their AirPods case.

It seems unlikely that people will routinely charge their AirPods from their phone when they could just as easily use the same charger that they just charged up their phone with.

The battery inside your headphones is negligible. Each (for Airpod Pro) is ~1% of your phone's battery. The case has a little over 10%, if charged from 0-100%