1) Air-washing a car that was too long in the hot Texas summer sun.
You open all the car's windows and drive for 2 minutes, then turn the A/C system's fan (only) on for another 1 minute, then close all the windows and turn the real A/C on, unless you are within 1 minute of your final destination, in which case, you can just turn the fan off and look for parking.
2) Something to attach your ski-poles to, when you a) get on the ski lift, b) open your water bottle, or c) want to help your friend back up!
3) A car seat that let you sit in it outside the car, and then it takes you to the inside like a toaster oven?
4) Using a Pi Pico RP2040 to implement the DCC protocol in the Programmable I/O (PIO), yes, just like that!