Although this thread is iOS 15, I guess its topic is universally valid.
I was searching for a solution that works without Homekit or WiFi but uses any other trigger (Bluetooth, LED, Sound, ...).
But then I looked at the chart again and suddenly it doesn't seem worth anymore... unless I read it wrong:
Assuming I need 30% charge per day, I can use my phone from 75%-45% and charge it daily.
> Then I have 87,69% capacity left after 6000 cycles.
Or I can use it from 100%-40% and charge it only every two days.
> Then I have 86,85% capacity left after 3000 cycles.
The more convenient latter option results in a battery health only worse less than one percent (0,84 %)?
EDIT: In regard of the high number of cycles, it's probably hard to apply the findings to phone charging.