Set up your burner in a coffee shop, restaurant or supermarket, using their free wifi.

Google is relentless. It associates phones which are in close proximity or use the same wifi. You can end up with people getting suggestions about your burner identity. At the least, Google will know to associate the burner you, with the real you. So don't bring the burner with your "real" phone - or your smart phone either - while on.

Remember, if you have a smart phone, it also knows where/when you are anywhere, and usually "talks" to Google with normal settings. Is your Google location log enabled?

There’s no reason to carry another piece of hardware in these times. You can get a free number on your device from Google Voice and there are others at a modest cost