If you own a supported Google Home smart speaker or smart display and are still waiting for the Gemini upgrade to arrive, your wait is over. The folks over at 9to5Google spotted this trick over on Reddit on how to force the Gemini update to happen. And yes, this is applicable for both Android and iOS.
To get started, just enter: googlehome://assistant/voice/setup into your web browser, which opens the Google Home app and starts the setup for the Gemini for Home voice assistant. If you’re using the Chrome web browser, select the 2nd option to avoid a Google Search. If you get the option to continue to the Home app, tap Continue, and proceed through the short setup process.
Once the setup is finished, your Home app and supported smart speaker or smart display are Gemini-ready. This will provide faster speeds and the new Gemini voices that Google promised. Enjoy!

