https://techcrunch.com/2019/02/24/the-google-assistant-gets-a-button/

Traditionally, the Google Assistant always lived under the home button on Android phones, but as the company announced at MWC today, LG, Nokia, Xiaomi, TCL and Vivo are about to launch phones with dedicated assistant buttons, similar to what Samsung has long done with its Bixby assistant.

The new phones with the button that are launching this week are the LG G8 ThinQ and K40 and the Nokia 3.2 and 4.2. The upcoming Xiaomi Mi Mix 3 5G and Mi 9, as well as new phones from Vivo (including the Vivo V15 Pro) and TCL will also feature a dedicated Assistant button. With this, Google expects that over 100 million devices will soon offer this feature.