Isn’t health data stored locally?

Not on iOS it doesn’t. They explicitly opt out of even iTunes backups made locally.

Even better, there’s been a case where Microsoft Support has used it themselves.

I don’t believe they can provide firmware updates once the chipset loses support, which is bad for security. (The same also applies for every other manufacturer, but Fairphone claims to update their phones for a longer time).

It’s unfortunate that Fairphone sucks in other ways (such as having limited firmware updates due to using an old SoC, as I understand it).

I hate how they blow fuses to permanently disable security features when the bootloader is unlocked.