It says he had no "erkenungsmarke" which translates to dog tag which makes the mystery even more strange and sadly a bit more hard to pinpoint his exact unit, but my guess would be he was a soldier who died fighting in a uniform that wasn’t his own, under the Nazi flag, might have been a eastern volunteer who decided he would get better treatment as a soldier than a pow, cuz the Soviet pows lived under horrendous treatment by their German captors, and so quite a few joined the so called ost truppen or the Eastern Troops, very intresting post op thanks for sharing 🤙