The Simple Sabotage Manual exists for a reason. Enough people in even the lowest level positions of the war machine's war industry or its economic forces, can do a lot of damage by just being intentionally not particularly competent. Don't be incompetent enough to be fired for cause, but make stupid mistakes. Enough people making enough stupid mistakes grinds a war machine to a halt, one grain of sand in the gearbox at a time. You might not be able to do overt sabotage, but you can absolutely screw things up by accident. Everyone has stupid little accidents at work sometimes. You weren't thinking. You didn't have your coffee yet. Everyone has a bad day now and then. No one has to know you're opposed to the regime, not just clumsy and slow.