You could buy a tablet
No need for cell connection ability.
Wifi tablets work perfectly.
But the app is very demanding.
You need to get a tablet with a fast enough processor and enough RAM to run the DJI Go4 app properly.
I believe I have it. Things like enabling intelligent flight as in waypoints, reading battery charge, seeing the drone position on the map and viewing the drone's camera, all is coming through the USB correction, correct?
Except for this particular item, you are correct. To see the maps, you either need to pre-cache them to your tablet while connected to wi-fi , or you will need to be connected to wi-fi or cellular during flight. Pre-caching the maps is easy, and if you do that you will have map view with wi-fi turned off and no need for cellular.
Just a note on that. Look for as much RAM as you can get. The specs for this model indicate ony 1.5MB of RAM. You really need at least 2MB minimum for GO4 to run efficiently without lag. 1.5M struggles with GO.
If you're going to buy a device, you might want to look at getting an Ipad, they pretty much work where it's hit and miss on what android device will work well. I've used android phones and tablets also a Crystal Sky and have had mixed results whereas the iPhones and Ipads unless there old work good.
I wouldn't throw $150 at a Fire tablet for flying, too proprietary... no access to Google Play unless you root it, OS is a heavily modified Android fork, and on my Fire 7 the USB port wouldn't act right.
I'm really happy with this Huawei Mediapad M3 8.4 and have read of others having luck with the less expensive T3
I've got a Samsung Galaxy Tab A6 made in 2016. It is just a wi-fi tablet not a phone. It has the Android 5.1.1 operating system. I have the DJI Go 4 app installed and it will connect to my Mavic 2 Pro but it will not transmit the camera view to the screen. Everything else seems to show up on its screen. But I don't use it because of this. When I use my phone, (Samsung Galaxy S8, everything works fine.