Why not create a Pip-Boy from Fallout 4 since all of the real ones are sold out? It could be running based off of a Raspberry Pi (or a smartphone). 3D printed to fit on your arm, and using basic buttons to control the Pi. Also the cord on the back of the PipBoy could be a USB rather than something to open a vault. Maybe also connect to bluetooth? (the PipBoy itself has a lot of area to fit things in)