The original version is run from an iPhone with an ios app. There is also a local control panel on the device that does the basic functions (e.g. fill/empty/pressure and a small display). But all the complicated stuff (dials, graphs, model parameters (e.g. fuel capacity) is done by the iPhone or the Jeti TX. The Argon does not have enough compute capacity for this stuff .. though it is convenient since it has a built-in bluetooth (and wifi) radio...
I understand your concern about the TX. So this might not be good for you. But just to be clear, there is no modification to the TX .. Jeti supports the UART ports on the motherboard from the new lua api, and the bluetooth module is attached to the back of the case with adhesive or velcro.
Lots of guys put bluetooth music players etc on the back of the TX and use them during flight. I have also used the bluetooth link in flight (after a lot of testing and consulting with the person who does the govt certs for Jeti equipment in the US) to pass the live telemetry information to an iPad for the spotter. It works really well since you have a much larger screen and much more compute power, and wifi and cellular and .. well you get the idea.
I am thinking in the future the only app I will run on the TX is one that downloads all the telemetry via bluetooth and do all the stuff I do with lua apps now in SwiftUI on the iPad...
Here are some pictures. Inside the unit, I am using four one-ways sensors in a "diode bridge" configuration since
the flow sensors are only accurate with flow in one direction. It's a 12V Greylor DC pump. On the PCB you can see the
Particle Argon processor (similar to Arduino, built-in WiFi and BLE), and the high-power DC motor driver. The main case is 2mm aluminum, laser cut, bent to shape and powder coated. The display unit on top is 3D printed from PETG. The unit hangs from a 20L fuel can and holds the battery pack.