So, uninspired by the progress on this issue, I am looking at an alternative. I am automating some other stuff and planning to use HomeAssistant running on a Rapberry Pi 3 B+.
This can be used to control Bose Soundtouch devices (apparently) and it can also be linked to Google Assistant (Google Home).
If I can get it working then I can link Google Assistant to my HomeAssistant and control Bose that way. In essence, the Home Assistant would just be a multipurpose automation hub that can control many other devices too.
May 29, 2018
Good news is that Sonos CEO Patrick Spence says that the integration of Sonos speakers and Google Home Assistant can be expected "later this year", with both parties working hard to get it ready in time for the holiday sales period. While I do like Bose better than Sonos the later's quality it more than acceptable as I get into my 50's and desire for clear sound at a level that allows for conversation is more important.
I got it working yesterday using a Raspberry Pi 3 running hass.io (Opensource Home Assistant).
The Home Assistant (HASS) can control the Bose Soundtouch devices and by doing some port forwarding on your router you can get Google Assistant to give voice commands to the HASS.
I have 4 soundtouch devices with on / off / volume and they are controllable via the Google Home app and Google Assistant voice control.
Next step is to get speaker groups set up and choosing the presets (at present it defaults to last preset used).
It took me a day or so to figure out all the details but it does work. total investment <$100.
I am looking to write up a guide to doing this as the ones on the internet have a few holes.
Nov 2, 2018
To Bose support - please add your SoundTouch speakers to google home assistant. I have three bose soundtouch 10 and one bose soundtouch 30 in all rooms and I will appreciate if you add this feature. Thanks from Bulgaria
Jun 6, 2018
Hello boyski! Thanks for posting and welcome to the Community.
I have passed your request to our development teams. Thanks very much for your interest in improving the features of our SoundTouch speakers. Have a great day!
Greg - Community Support
Nov 3, 2018
Nov 10, 2018
Feb 27, 2018
So disappointing we don't have an official response from Bose.
I have a setup working -
Google Home Mini for the Google Assistant.
Chromecast Audio plugged into Aux jack on my Bose.
The Chromecast set in the Google Home app as the default speaker for the Google Home Mini.
It works, but I'm wasting a ton of features of the Bose and using it just as a "dumb" speaker. A much lesser Bose product could perform the same function.
Yes, I am stil hang on to the hope Bose will get their act together regarding Google Home. But sooner or later I'm going to have to make the call. Alexa is rubbish compared to Google Home so If Bose don't do something about this soon I'll be selling my Bose sound touch/Alexa and switching to Sonos and Google Home!