In the latest beta version of the app Google, version of the website 9to5Google have found mention of headphones under the code name Bisto.
Bisto is headphones that Google Assistant. In application code it is said that on the left earpiece there will be a separate button to call a smart assistant Google. Likely, Bisto microphone is always active and the user will be able to call assistant’s voice.
The owner of Bisto will be able to fully use all functions of Google Assistant. In application code it is said that the assistant will be able to announce incoming notifications using Bisto, and people will be able to answer them.
It is not known when Google will release headphones. Perhaps they will be submitted along with the Google Pixel 2 in the fall of 2017.