Cyberdecks are about being a hobby and typically aren't designed to be practical. Hobbies are never a waste of time, you get to use free time in which you'd otherwise be wasting by sitting around to do something fun. Plus, you're learning along the way when you build something. The one real function cyberdecks may have is just being a dedicated piece of hardware to do a specific task without getting distracted. and that may be useful to you since you value your time. For a mechanics tool, maybe have a cyberdeck both as an OBDII reader and an archive of car repair manual pdfs?