Guaranteeing updates for X years is an empty promise unless they also guarantee the maximum delay in adopting upstream (security) updates and releasing them, with reimbursement in case of failure to comply.

The focus of Android One seems to be running an unmodified Android? I don't think there is an emphasis on a minimum hardware spec. The phones showcased there do impress.. https://www.android.com/one/ Is there a requirement for how long the phones are supported with software/security updates?

If I were to add to the brief spec I defined above I'd also require speakers at both ends of the phone for stereo output, and require keeping the 3.5mm jack (yay S9?). I still think Samsung likes to make slippery bar-soap phones that I cant hold.

I still don't like how permissions are done even on LineageOS - I wish I could grant access to the camera for an app "for the next 5 minutes".

Now I'm really off topic. I shall diminish ~

Android Treble is, at long last, decoupling Android OS porting from the cycle of BSP support. It's only for Android 8+, so the impact won't be widespread until later this year and into 2019. But this should enable vendors to lengthen their update support more independently of the underlying kernel and driver support.

https://source.android.com/devices/architecture/treble

Large parts of Android-the-OS is implemented in middleware running on the same runtime as Android's apps, which should have made this kind of portability possible earlier in the development of Android. But here it is.