Typical machine shops do not have the capabilities to make composite armor, gas turbine engine components, aluminium oxynitride vision blocks, night vision equipment, thermal IR sensors, encrypted radios, targeting computers, MEMS/laser ring gyroscopes, high precision servos, or range finders. Without these parts, you have a target rather than a tank.

All modern production has bottlenecks. For items that governments consider important, they find ways to manage bottlenecks.

The issue with US N95 availability is that no one in authority considers the problem important enough to be worth fixing.