Re-read the article. All this feature does is give you the ability to say ‘set a timer for 10 minutes’ or ‘start a phone call to John’.

If you have ‘Gemini apps activity’ off then they won’t use anything you say to train their models.

You can turn it off by going to Settings > apps > default apps > digital assistant > Google > none.

You should disable the Google app entirely while you’re at it.

Gemini can be disabled. Uninstall/disable the Gemini app if your phone has it then go to Settings > Apps > Default apps > digital assistant > Google > none.