Google only sold Nexuses and Pixels, which compare very favorably to Microsoft's Kin phones in continuing support.

Agreed. Google is really good at back compatibility - sometimes even to a fault.

It also seems Google sometimes is held to a higher standard when it comes to supporting products long after they are out of service.

Compare that to Microsoft and Windows Phone for instance, or UWP, or even Windows... it's a big mess with millions of outdated and insecure devices.

During Windows Phone's lifetime devices were rarely left un-upgraded or out of security support. Not quite as well as iOS, but much better than the Android situation. Arguably it was one of the reasons that phone carriers chose to kill Windows Phone because they seem to like being able to micromanage the tire fire that is Android Updates and Windows Phone was too "uppity" for them.

UWP isn't "dead" and its technologies continue to get updated.

Windows' left behind devices that no longer receive security updates are after at least a decade of active security support. XP was offered several lifelines, way beyond the security support of any single Android version in the history of Android. Windows 7 seems on the path to similar lifelines and maybe won't have quite the same record of security support, but will still see active security patches for much longer than any Android version could imagine.