Nick Chopper wasn’t a soldier. He was a woodcutter. Once his body had all become tin he remained a woodcutter. He continued to carry his axe less for utility than because it was the last remnant of his human life.
After the events of World War 2 he set his axe aside and built other weapons into his body. He used the latest technologies to make his bodies into mobile defense/assault systems.
There was a Tin Soldier in original Baum Oz books. I don’t know if he’s still around. If he is, he isn’t scheduled to appear in Oz Squad yet.