Earlier quoted context omitted.
Less than 5% of phones currently run Android 6.x. I don't really think that's a fair "requirement" to give to people, given that many people are otherwise prevented from getting a Marshmallow update not because of the age or model of their phones, but because the carrier has prevented it.
If someone was truly that concerned, they'd make the choice to buy a Nexus device for that protection rather than embrace a 3rd party device with manufacturer and carrier crud.
1. Purchased the device at a major electronics reseller during a period of specific contingency whilst travelling.
2. Prefers strongly to avoid mail-order purchasing for numerous reasons, including the possibility of in-transit interceptions and undocumented third-party enhancements.
3. Couldn't find a Nexus device at said major retailer.
4. Isn't aware of Nexus devices which offer expandable storage. Device in question has 128 GB of MicroSD storage. Max possible Nexus is ~16-32 GB last I checked, with no expansion possible.
I've explored other options, including a CyanogenMod reflash, though that's less than straighforward.
So, unfortunately, the world involves numerous compromises. I treat the device as hostile though of some utility. I've pressed several other app vendors on permissions, and am batting somewhat above 0.500 for having those reversed.
I've also vented considerable spleen at Google over how it manages Android. Given my previous record with recommendations, I expect to be fully vindicated in about 3-4 years.