I have a 6th gen 12.9 iPad Pro that’s WiFi only, and I recently upgraded my mini 6 to a mini 7, that’s WiFi only. I use the hotspot from my iPhone, which I haven’t had any issues with. My battery in the iPhone is the least of my problems. I carry a portable Anker charger, so I can charge both iPad and iPhone at the same time several times if need be. I use my iPhone for gps when traveling.