The Google assistant is available to Android 6.0 and above. Most of the devices should get it without doing anything. But some Hawaii and Xiaomi devices that I've had my hands on didn't have this feature.
To get the Google Assistant, try following these steps.
1. Become a beta tester for two apps
2. Google Play services
3. Google
4. Change Device language to the USA
5. Reboot
2. Google Play services
3. Google
4. Change Device language to the USA
5. Reboot
After reboot, go to play store>My apps & games>Beta. Now you should see both apps are being updated.
P.S: You have to log in to Google to become a beta-tester and use the same ID for play store.
I'm not giving a guarantee. But I haven't encountered failure with the phones I've had hands-on.
The contribution goes to my friend Abir, who taught me this.
