Wifi only won't help because other peoples phones have precisely geotagged the location of wifi hotspots, and your phone is likely reporting wifi signal strength to the mothership.

Ah, yes. So basically, you can't use your main phone anywhere and for anything that you don't want linked to you. You need one or more secondary phones, purchased as anonymously as possible. Each of those must only be used in specific locations for specific purposes, and otherwise stored in a Faraday bag or box. Perhaps only once, as a "burner phone". In other words, phone use must be compartmentalized. If it matters to you, anyway.