Did those POWs end up as U.S. citizens?
I grew up near there. There are many stories about some of the prisoners "escaping" from the camp at night to go to the local watering hole...and then going back "home" to the camp. The local population was/is majority German ancestry & it would not have been uncommon for some of the older folks to still be fluent in the language. Don't get me wrong; many of these families had sons in the war FIGHTING the Germans and they were very patriotic.
But, many of the POW's, from what I gathered were pretty damn happy to be in the camp instead of the war, & would have found the local culture to be fairly familiar. Most were sent back to Germany...I suspect not all...it would have been easy to "blend in."
Quite a few DID become American citizens and rabid ANTI-Nazis after seeing how the regime lied to them.
Many of them became citizens. They realized even their interment here was far, far better conditions than what they had in Germany.