I guess it was bound to happen: Google Assistant is finally breaking free from the shackles of the Pixels and launching onto the millions of devices running Android 6.0 Marshmallow and above, no need for GApps or root.
But this shouldn’t come as a surprise to you. The signs were there all along. Despite being revealed as a Pixel exclusive on phones in the Android 7.1 changelog, Assistant has been available through Allo on all Android 4.1+ phones, announced for all Android TV 6.0+ devices, and was shortly enabled by mistake through an alpha version of the Google app on non-Pixel phones.
Google Assistant is coming to all Android 6.0 and above devices was written by the awesome team at Android Police.