According to this Sonos article, Google Assistant isn’t available on Sonos in Portugal. But it is available in Spain. You should consider changing your country in your Sonos profile to Spain.

Read more here:

https://support.sonos.com/s/article/3491

The Google assistant availability on Sonos is shown here:

https://support.sonos.com/s/article/3491

If your Country is not presently listed, you are probably best, as a Google customer, to contact them direct and let them know that you would like the service and hopefully, with enough customers requesting it, Google may then go onto add the service to your region.

Thank you for your reply. 
I’ll do it