On top of the complex communication layer we're trying to avoid? Umm, I'm not suggesting to run an aux cable or serial connection on top of a TCP stack, so I do

On top of the complex communication layer we're trying to avoid? Umm, I'm not suggesting to run an aux cable or serial connection on top of a TCP stack, so I don't understand what you're saying Edit: or do you mean the other way around, namely running a network stack on top of this (e.g.) serial connection? Also not what I meant but I wasn't explicit about that so this confusion would make sense. What I had in mind is doing whatever comms you want to do with the airgapped system, like logging/storing the diplomatic transmissions or whatever this system was for, via this super simple connection such that the airgapped system never has to do complex parsing or state machines as it would with something like USB or a standard kernel's network stack