https://arstechnica.com/gadgets/2017/12/google-assistant-comes-to-older-android-phones-running-5-0-and-up/

Google's push to put the Google Assistant everywhere continues. The company's voice search interface exists on phones, watches, TVs, cars, and in standalone smart speakers, but the company has never done a great job of capturing the entire 2 billion-strong Android market. The Assistant originally launched on a single phone, the Google Pixel, and has slowly been creeping across the Android landscape.

Now the Assistant is coming to even more Android devices. Google announced the voice assistant is coming to older phones running Android 5.0 Lollipop and up. This is a big bump over the old rollout, which only included Android 6.0 Marshmallow and up. According to the Google Play active user stats, Lollipop compatibility will add another 26 percent of Android's install base to the Assistant's reach.