Ever since Google debuted Google Assistant with Pixel smartphones last year, it has been discussed a number of times if and when it will be expanding it to beyond Pixel. But with the latest Google alpha release, it seems like it might happen in the near future.
The latest Google v6.13 alpha release is found to have been enabling Assistant for some non-Pixel smartphones. Android Police has spotted Assistant to be running on the Nexus 6P on Nougat 7.1.1 and the Samsung Galaxy Note 5 on Marshmallow v6.0.1. You can refer screenshots shared below.
The procedure for enabling Assistant after installing Google v6.13 alpha is exactly similar to Google Now on Tap/Screen Search. You simply need to tap and hold the Home button which will show a pop-up “New! You just got the Google Assistant.”
As mentioned above, Assistant has been spotted on some non-Pixel smartphones. It seems like Google is enabling it for random users which mean there is no surety that it will work on your particular device.
Other than this, the same Google alpha version brings a bunch of new features like support for Payments in Google Assistant. There is also a Lite mode which is meant for slow internet connections and a page for recent search topics.
If interested, you can grab the Google v6.13 alpha APK from APK Mirror but do remember that it’s the alpha build. It means it can be quite unstable for daily usage.