If you look closely, the stripe along the edge of the lapels suggests that he was probably an NCO, but I'm personally unsure what grade. 1st Sergeant does seem within the realm of possibility though, at least.
Additionally, he also seems to be wearing the Waffenfarbe (branch-of-service colors) of the Pioniere, who were the engineering corps of both the Reichsheer and the Wehrmacht
If you look closely, the stripe along the edge of the lapels suggests that he was probably an NCO, but I'm personally unsure what grade. 1st Sergeant does seem within the realm of possibility though, at least.
Additionally, he also seems to be wearing the Waffenfarbe (branch-of-service colors) of the Pioniere, who were the engineering corps of both the Reichsheer and the Wehrmacht