My phones have been destroyed not by ageing batteries but by bloating software. You need to update software for security reasons, but those updates also take up more space and run slower (because developers work only as hard as is necessary to make apps run acceptably on their phones, which are typically new models). Space bloat, more than time bloat, has been the biggest issue.

Open bootloaders and drivers (after a certain number of years at least?) would help with that. Make available enough to let open source developers help themselves. Even if Google stops supporting Android on my hardware, or Apple stops supporting iOS, there should at least be a stripped down Linux?

I'm not sure how useful even that would be though, because that surely won't be able to run the latest apps used by society.

Sigh. Maybe everything is just an arms race. Phones won't stop going obsolete until it is physically impossible to make faster phones.

Since space bloat has been a bigger problem than time bloat, I could maybe have gotten more life out of my phones if the OS had supported the installation of apps to the SD card. Maybe that could be a cheap partial fix.