adding it to Android Messages. Certain handsets offered to Google's Project Fi subscribers had first crack at the new capability found in the Android Messages app. Let's back up a step first and explain what Smart Reply is. On Gmail, you might receive a letter that is seeking a response from you. With Smart Reply, there are three pre-written choices at the bottom of the missive, and each one would be an appropriate response. You tap on the one that you think matches how you would respond to the email, and that's it. No fuss, no muss. Keep in mind that you are not forced into using Smart Reply, and you can write your own answer instead.
On Android Messages, the same concept basically applies. In the messaging app, the Smart Reply choices are offered after the person you are messaging with sends you a text that seeks your response. According to some on Reddit, Smart Reply is available with Android Messages on Android phones as old as the Nexus 6P.
Smart Reply is expected to continue rolling out to more Android phones. The update is being disseminated via a server side update. If you wish hard enough, it might come soon to a handset near you.