Assuming the controls are the same as the Model 3, you can use the lever on the steering column to shift into neutral. It's not a mechanical solution, but it is doable without using the touchscreen.
Edit: just out of curiosity I went to look at photos of the Cybertruck interior. No levers on the steering column. WTF. That alone would be a deal breaker for me.
holy shit I thought I was kidding but this thing doesn't have an off button, from pg 72 in the owners manual (note that shifting into park is also a touchscreen button that displays when stopped)[0]:
When you finish driving and shift into Park, simply exit the vehicle. When you leave Cybertruck with your phone key, it powers off automatically, turning off the touchscreen.
Cybertruck also powers off automatically after being in Park for 30 minutes, even if you are sitting in the driver's seat.
Although usually not needed, you can power off Cybertruck while sitting in the driver's seat, provided the vehicle is not moving. Touch Controls > Safety > Power Off. Cybertruck automatically powers back on after a short period if you press the brake pedal or touch the touchscreen.
my gripe with touchscreens is they're no good in an emergency, you want an interface that reacts well to being grabbed :)
does the cybertruck even have a proper "off" button or does it just read your mind to anticipate when you want to put it in standby mode? :p