Although the latest Pixel Launcher app was made to work with Android O Developer Preview, one XDA Forums user made it available for download to those running at least Android 6.0.1, who should be able to have the launcher up and running quite easily.
http://www.notebookcheck.net/Unofficial-Android-O-Pixel-Launcher-available-for-Marshmallow-and-Nougat.209176.0.html