Google releases Android 7.0 for Nexus 6
Google has released Android 7.0 as an update for the Nexus 6. Almost all other devices in the Nexus series already had the update. Android 7.0 Nougat officially came out in mid-August, but the update was delayed.
It is unknown why the updates took longer, but presumably the Android 7.0 firmware still contained bugs that Google first wanted to fix before the update would come to devices. Android 7.0 comes as an ota update on Nexus 6 copies and Google has also put the ota file and factory image for the Motorola smartphone from 2014 online.
The firmware has the serial number NBD90Z. The first developer preview of Android 7.0 for the Nexus 6 and other devices was released in March. The Motorola-built Nexus 6 and the HTC-manufactured Nexus 9 LTE are the oldest devices for which Google is releasing an update. The Nexus 5 and Nexus 7 2013 will not get the update and will be stuck on Android 6.0 Marshmallow.