Seems like most people who have a cellular plan would have a cellphone. It's really easy, and free, to connect your iPad to the internet via your cellphone hotspot. However, I would recommend getting an iPad with internal GPS just incase your ADS-B device fails and also so you can use the iPad with Google Maps or Waze for navigation in your car.
As an aside, I just saved $2,000 on the purchase of my wife's new car by NOT getting the navigation system with backseat entertainment screens. Carplay works great with Google Maps, Waze, and Apple Maps just by plugging her iPhone into the car's USB connection. And, your maps are always up to date.