Google has started rolling out Android 7.1.2 (Nougat) beta update for several Nexus devices and Pixel devices including Pixel and Pixel XL, Nexus 5X, Nexus Player, and Pixel C devices. The Nexus 6P is also eligible, but it will be released soon.
Google Nexus 6 and Nexus 9 will not get the update, and the Android 7.1.1 will be final. This is expected since Google already confirmed that there are no guaranteed Android updates for these devices after October 2016. Both these phones will still see security patches going forward for close to another year.
The update brings refinements including a number of bugfixes and optimizations, along with a small number of enhancements for carriers and users, says Google since the Android 7.1.2 is just an incremental maintenance release.
Android 7.1.2 is currently live for Pixel and Pixel XL, Nexus Player and Pixel C which can be downloaded from Android developer website here. You can also get it through Android Beta Program, which is the easiest way to get it. The final Android 7.1.2 update for the supported devices will be released in a couple of months.