My grandfather was one of these Russian POW. He was 15 years old. Conscripted and sent to the front without a choice.
He said, he only survived the camp because he met his uncle there. That’s about all he was willing to talk about it.
In the first war years my greatgrandfather (his father) spent 3 years in prison because he spoke not favorably about the Nazi regime. No trial, no visits, no information. Everything he owned, including his business was expropriated by the Nazis.
He was supposed to be moved to a camp but then was suddenly released without any information and conscripted into the army.
Neither of them had any choice. Mere soldiers, the ones in the trenches, generally didn’t.
People were executed for refusing military service and after that they sent your whole family into a camp for “Sittenhaft” (kin collective punishment).
The SS and SA who were responsible for unbelievable atrocities were only a part of the German military. They were the “elite” units.