It’s much much much cheaper to use the same 12V systems that other cars use.
Kia/hyundai solved this by having a disconnect on their (li-ion) 12V battery. When the voltage gets low it completely isolates the battery. There is a button inside the car that reconnects it right before starting the car.
I’d love to see a crank on EVs to power the low voltage stuff in emergencies. How many amps does the car startup take? 15A? Maybe bicycle pedals.