If the United States had the capacity to make enough ammunition and ordnance to fight multiple wars at the same time, there would be enough people employed by these companies that you would probably personally know at least 1 of them.
All those places together do not even employ 400,000 people. I work in manufacturing and I don’t know a single person who works at these places. What I’m saying is so many new jobs would be created that MILLIONS of people would from that point on be in the defense sector making bombs and bullets. It’s not even comparable.
Walmart is a big employer. Can they supply war munitions? Being a big employer is genuinely irrelevant unless the bulk of those employees are making munitions