Will it provide enough power to jump-start a truck engine?
Extremely unlikely. First get its own battery charged, connect that to a larger battery, and get THAT well charged. This could take many hours with only a flywheel magneto/generator available. Then do your "jump start" with the second one. In your scenario try and work up in stages - get a small forklift running first, then go for something bigger - an aircraft tug perhaps? Many forklifts run on Propane gas - this won't "go off" like unleaded petrol, and they have simple carburettors, probably very basic ignition as well. While you may not be able to push start one, you've a fairly good chance of starting it with a reasonable battery. That would give you a 30-50 amp alternator to play with...
Also note that any car with an alarm/immobiliser is going to be useless after a period of months. Many won't start after a few weeks in a long stay car park. A few tens of milliamps might not seem much, but multiply by 24 hours a day for a month, and you've a completely flat battery. And once it remains in that condition for several weeks it will suffer from sulphation, and never recover...