Unofficial Android O Pixel Launcher available for Marshmallow and Nougat
Android O Developer Preview also includes the new Pixel Launcher app. However, those who do not want to test the entire new mobile operating system can now grab only the app and run it on devices that use at least Android 6.0.1 Marshmallow.
According to XDA Forums user linuxct, the app he made available for download last week "is just a quick backport to get latest Pixel Launcher from Android O Preview 1 (version O-3743572) theoretically working on Android 6.0.1+ (tested on a Wileyfox Swift 2+ running CyanogenOS 13.1)."
Those adventurous enough to try it should know that all previous versions should be removed first, and the app forcefully exits on the first run in most cases but works on the second try. This happens due to the fact it needs to generate a file required to run.
Considering the users' feedback, it looks like most handsets with Marshmallow or Nougat on board should be able to run the Pixel Launcher app for Android O smoothly.