Adafruit makes a cyberdeck HAT for the pi400 https://www.adafruit.com/product/4863 It's definitely not the same aesthetic as what people think of as a cyberdeck, but as far as retail cyberdecks go, it might be the closest thing.
if you are 100% sold on a single 3.5" screen and no gui, then it will work. outside of that, it's a novelty item