Hi @dudeviper, welcome to the Sonos community, and thank you for letting us know about your concern. Let me help you with this.
You can stream music to your Sonos One SL using the Sonos app. Streaming from your MIBOX to your Sonos One SL is not possible since they are using 2 different platforms. Streaming from your Android TV is possible if you have a Sonos soundbar connected to it. On Google Assistant, you can set up a Google Assistant-enabled device, like a Google Home or Google Home Mini, to control Sonos. Once set up, you can use the Google Assistant to play music to Sonos, skip songs, pause playback, adjust the volume, and more. I'd like to isolate the issue so we can create a path towards resolution.
1. Is your Sonos system up to date?
2. Are your Sonos speaker and Google Nest Mini connected to the same WiFi network?
3. Have you tried commanding Google Assistance specifically like saying "Hey Google, play (the title of the song and artist name) in the Office (speaker name)."
To see if this clears up the issue, I would like to have you remove Google Assistant from your Sonos devices, and then red add it back. Does the issue still continue, or does it seem to improve? You can also run through our troubleshooting guide.
We would like to have you submit a diagnostic of your system and reply back with the confirmation number. This will allow us to see how your system is functioning, and help provide a resolution. If you need help with any other information, feel free to reach out.