So having read a fair chunk of the 800+ posts now I have come to a conclusion, since I am shopping for a new phone right now. Right on cue my android phone, 23 months old - lease plan about to expire, when upgraded to 7.1 Oreo suddenly lost half its battery endurance, from about 24-30h to 12-18h and charges at half the usual speed - nothing else changed except the OS. This is materially no different to the Apple story. I could revert to the older OS with a factory reset etc, and replace the battery, and thus temporarily overcome the planned obsolescence, but it will only buy me a year or so until a "critical vulnerability" that requires an OS upgrade will make me chicken out and upgrade the phone. This happened last time. The opposition are no better, if not worse, than Apple, but I unfortunately do not believe that Apple is about to come good on all this.
I am sick of giving them so much money for such short lived devices. So my plan is buy a mid-range android phone and treat it like a proper computer that it is: root it, remove the bloatware, install a firewall, etc, and replace the battery every two years. If the OS is properly locked down then nearly all the exploits don't apply, I guess.