I ride a class-3 Tern cargo bike with 400Wh battery and this range is very optimistic, especially since this is pedal-by-wire. Also what happens when the battery runs out, because you can just ride without assist on any Bosch e-bike.
Game over with a dead battery, I would think, though I suppose it's possible that the generator you're pedaling is enough for very slow movement without the battery boost...