Beginning with support for the Nexus 5X, Nexus 6P, and Pixel C, the Preview brings a number of the Pixel’s features to these older devices, allowing developers to test Android 7.1 features in their apps.
These include circular app icons, app shortcuts, image keyboard support, and software A/B testing.
Released as Android 7.1.1 for the supported devices, Google says the Developer Preview represents “beta quality” software, and finalizes the APIs at Level 25. Thankfully, Google is now encouraging developers to update their apps to support Android 7.1 on Google Play, so Pixel owners will start seeing circular app icons and app shortcuts on third-party apps in the coming weeks.
Google also says the Developer Preview will be expanded to the Nexus 6 and Nexus 9 before Android 7.1 is released publicly in early December.