I have it on good authority that (a) the reason the Chinese soldiers who were sent to reinforce the North Korean army were so ill-equipped is because they had been staged for an attack on Taiwan, and therefore had no winter clothes, and (b) somewhere around 20% of the surviving PLA soldiers sent into North Korea defected to the south during and after the war.
On a related note, here’s a video about an Italian army that landed in Normandy.
https://youtu.be/39BhaqucJzg?si=_fiXOsz24eGJeurL
These Italians were on the Allied side at this stage of the war, and served in non-combat roles.
“...that he had been sent to a prison camp in the UK and emigrated to the U.S”.
I read where the Soviets took in a lot of German prisoners and worked them as slaves for years to help rebuild the USSR. If he had been in the Soviet army, I would have expected they would have had first dibs on him.