On Youtube there was an open invite to come in and offer suggestions for a build.
Recently these specs were put up.
https://all3dp.com/3d-printed-fallout-pipboy-3000/
Right now these so called Pipboys and the one Bethesda made are nothing more than fancy cellphone cases but I bet Ben could do a lot more.
Take a Pi and use that case as the foundation then build a wrist mounted microcomputer controlled using buttons and dials with as much functionality from the game as is reasonably possible.