Yeah - I remember when I was a volunteer firefighter - if you parked a fire truck in an atmosphere that was filled with combustible gasses, the engine would not shut off.

The trucks were equipped with some type of an emergency throw should that situation ever arise. We never had to use it in my time there.

Diesels don't require spark, but modern diesels use electronics for fuel injection, fuel pump, drive-by-wire throttle, engine monitoring, and so on.

Since at least the ~2000 era, a VW diesel will run with no alternator (for a while) but not without a battery.