The world got its first glimpse of Google Assistant at this year's I/O conference and later was available to users through the Allo messaging app. There's no doubt that the built-in Google Assistant feature is the biggest highlight of the Google Pixel and Pixel XL smartphones and will remain exclusive to these phones until Google rolls out the feature to non-Pixel devices.
Google has confirmed plans to Gadgets 360 that the Google Assistant feature will be coming to other phones though has not revealed any timeline. The Assistant, very much like Google Now, will be present on the home screen and can be launched by a long-press on the home button. It will come with AI smarts and will be able to contextualise the information it digs up through earlier interactions with the user. While Google may not have revealed plans to bring the feature to non-Pixel devices for now, but there's a way users with Android Nougat running on their devices can use the Assistant. It works with rooted smartphones, as well as those sporting a custom recovery.
XDA Developer forum member Brianelv has posted a short guide on how to enable Assistant on non-Pixel device running Nougat. Before proceeding make sure to take a full backup of all your data and proceed at your own risk. For those unaware, the beta program is the simplest way of getting the Android Nougat on your device though you can follow our guide to manually download the Nougat update. The smartphone is required to run Android 7.0 Nougat or higher version with the Google app version 18.104.22.168 or above installed.
Once you have these prerequisites, you will need to tweak the build.prop file, or install a flashable zip via custom recovery. This will work for users with devices that are rooted and a change to product model will be required. Just add or replace these lines on your build.prop: "ro.product.model=Pixel XL" and "ro.opa.eligible_device=true." After the tweaks to build.prop file, you will have to reboot and clear Google app cache. Once cache is cleared, the device should allow you run Google Assistant and can be accessed via long press on the home button.
As for the flashable zip file, XDA user @FaserF has posted a guide on how to use it, as well as the link to the zip itself.