While you can leave your iPhone at home while you run, go to the store, or stroll on the beach, you must have an iPhone turned on and connected to the internet at this other location. This is one reason why connecting to an iPhone and switching to an Android makes the Apple Watch useless with an Android phone.After initial setup, a cellular-enabled Samsung Galaxy Watch or Google Pixel Watch can act as a stand-alone mobile device. With the latest Galaxy Watch 7, Watch Ultra, or Pixel Watch 3 running Wear OS, many more apps can be used on the go, so you can leave the phone behind in most cases.