I’m having the same problem as of 2 days ago.
Have tried the same as you.

Hope there will be a fix.

Hi ​@Alexal 

Welcome back to the Sonos Community!

I am sorry to hear of this issue you are having with adding Google Assistant to your Beam (Gen 2).

We are aware of an issue currently preventing users from adding Google Assistant to Sonos devices while using a (possibly newer) Android device. It seems to be linked to Gemini - some time ago, we noticed that Gemini had to be disabled (in favour of Google Assistant) for the process to complete. Now, it seems it does not help.

Google Assistant can still be added to a Sonos speaker using iOS, or Android 9 (according to one customer, at least), if you have one of those available.

The issues seen with Google Assistant do not appear to be limited to Sonos, which a quick search will reveal.

We do not have an estimate for when this might be resolved, but I will update this thread when I hear of it.

I hope this helps.

Ok thank you 

Hi again.

I went out and bought an old android phone with Android 9 on it.

This did not work ! So no solution.

I was going to buy more speakers but now i am very hesitant about this as i use google all over the house.

I’ll therefore be looking in to other speakers as there is no popper solution and no fix in the horizon.

Thanks for the update. 

I tried also with IPad 4, without luck. Sonos app doesn't support old IOS devices.