I understand your conserns.
Normally this setup requires some linux skills and network knowledge to get this going.
However, if you do have the right spirit, and are willing to learn some simple linux commands, you should be good to go.
An UAV flight controlled ny cellular network is just awesome. laugh
Where are you from?
The first thing you should check is if your cell operator can supply you a sim card with public IP. "no port restriction"
You need a open line to get the communication between your aircraft and Ground control station. Thats first priority.
If you want to use Pixhawk, the communication path is as follow:
Pixhawk Telemetrty port -> Simple Serial to eth converter -> Raspberry Pi with cell adapter -> Your laptop with mission planner and e.g usb gamepad controller.