Google just posted the Android security update for April 2017 and the files are already live for a number of devices.
So far, we are seeing 7.1.1 files for Pixel and Pixel XL (NOF27D), Nexus 6P (N4F26U), Nexus 5X (N4F26U), Nexus 6 (N6F26Y), and Nexus 9 (N4F26X).
In other notes, the Nexus 6 is also seeing builds of NBD92F and NBD92G (7.0.0).
You can grab each image or OTA file at the links below. For instructions on how to flash a factory image, here you go. For instructions on how to flash an OTA .zip file, here you go.
As more files arrive, we’ll update this post.
UPDATE: The OTA files are now up as well.
UPDATE 2: Android 7.1.2 just went stable too! You can find those details and files here.
UPDATE 3: Special Verizon images for the Pixel and Pixel XL as build NHG47K are now available.
Links: Factory Images | OTA Files | Security Bulletin