You state “it doesn’t work it just pops up help info instructions on how to set it up ”. Where in the next steps does this happen? https://support.sonos.com/en-us/article/set-up-a-google-assistant-device-to-control-sonos

Do you have Google Gemini set up on your iPad? Could you use a phone for this set up?

I was never able to actually add a voice assistant in the Sonos app. When I click on Add Voice Assistant it shows the options for Alexa and Google Assistant but when I click on either of them all it does is option up Quick Help instructions on how to set it up. Is that what it’s supposed to do? 
I will try and install google gemini. My phone is an iPhone so I don’t think that using it or my iPad would make any difference but I will try that as well.

I installed Gemini but have no idea as to how this would help in this situation. It doesn’t seem to have anything to do with interacting with either the google nest or Sonos.

I’ve read in other posts that having Gemini installed could prevent the installation of Google Assistant. You could try temporarily removing Gemini from your iPad. See 

Okay, I just added Gemini so, I’ll just delete it.I’ve set my Sonos speakers as default for my nest. If I ask hey google what time is it - the nest device tells me the time. If I say hey google play music it says okay playing music in living room and I get zero music playing. 

I tried setting it up using my iPhone. In the Sonos app on the iPhone there isn’t even an option to add any voice assistant. I set up google assistant and home and Sonos app. The google nest still never uses the Sonos speakers.

I tried unplugging google nest and the speakers for an hour and plugged them all back in and it finally worked to play a Tune in Radio station. I wish I would have done that sooner. I don’t think any of the other stuff I did made it work. 
 

if it doesn’t work try unplugging everything for a while.

You’ve set a Sonos speaker to be the preferred speaker for the Nest?

Yes, I set the Sonos speakers to default on the Nest. it only worked once for Spotify and now that doesn’t work. It says playing whatever I asked for on Spotify but then there’s no music at all from the speakers. It only works for Tune in Radio. I have no idea why it doesn’t work properly.

I tried YouTube music this also only works on the nest speaker and will not work on Sonos. It says “sorry I can’t find what you asked for” when Sonos skeaper is set to default.

Well, after trying to get Sonos speakers to work with google nest for a few days I’ve given up. It seems they are just not compatible. I can only get it to play Tune in Radio. Why? I have no clue.
The fact that the Nest will play a song from YouTube fine but then setting the Sonos speakers as the nest’s default speaker causes it not to play the exact same song is well, just stupid. It also won’t play anything on Spotify even though it did play one song one time. It also can’t play anything on Sirius. Maybe the more recent speakers are more compatible. 

I’ve seen lots of other posts on here complaining about the same kind of issues. I don’t know if these issues are caused by the Google product or the Sonos product or both.

Too bad, It would have been nice to be able to play songs on my older Sonos speakers using voice commands.

Strange. This worked well with my son’s IKEA Symfonisk.