Latter was possible but non-trivial, with a good chance of ending up with a brick. IIRC installing a custom OS to get recent security patches never worked (it was abandoned on Android 6).
It would be really cool if in the $CURRENT_YEAR we could finally get unlocked bootloaders for all of our phones and actually own the devices.
But that's unlikely to ever happen with the way how Android and manufacturers treat the OS, much like how the driver situation is nowhere near where *nix is.
I have been on the iPhone 6S+ since inception. But upgraded to the 7S+ only for the water proofing...
Its the only phone I like... but the 6S+ didnt have the facial survellience NSA option. Thus I held onto that for a long time.
They are very durable, yes, but they don’t care about supporting them long term, software-wise.
Sign me up!
LTS Android (or iOS) with five+ years of security-only updates would be the perfect phone for them.
Much shorter time you get updates than even Samsung, forget Apple.