The claim from the article is that a fixed 'charge to 80% feature' is "likely possible on earlier models". I asked Apple to comment and am curious what they say. We do have evidence for the article's claim: iPhones dating back to at least the iPhone 8 support a feature that limits charging to 80% for multiple hours per day already. It just only occurs during hours Apple chooses via its learning algorithm. I never claim that the hardware is/is-not different; you simply have to look at what is already supported to understand what the devices are capable of.
The claim from the article is that a fixed 'charge to 80% feature' is "likely possible on earlier models". I asked Apple to comment and am curious what they say. We do have evidence for the article's claim: iPhones dating back to at least the iPhone 8 support a feature that limits charging to 80% for multiple hours per day already. It just only occurs during hours Apple chooses via its learning algorithm. I never claim that the hardware is/is-not different; you simply have to look at what is already supported to understand what the devices are capable of.