The majority of Chromebooks could have Google Assistant installed on them, after a commit made in Chrome Gerrit.
XDA Developers first spotted the post with a commit saying, ‘add Assistant feature flags changes accordingly’. XDA reports this is seeming to be the base for native Google Assistant integration of Chrome OS devices.
As of now, Google Assistant is only available on Google’s Pixelbook and Android phones.
This update seems to only be for Chromebooks and maybe in the future could be for Chromebases and Chromebits.
No word on when it will happen but probably sooner rather than later.