About an hour in to the mission I discovered that Nazis are actually kinda dumb and you don't really have to be very careful at medium difficulty.
Also, i don't understand why there are non-lethal options in this game, but I suspect there may be liberalism afoot.
I should note - If I did knock a Nazi out I specifically went back and shot them in the head. Those ten guys were accidents. Would have gotten them if I could.
Sniper elite introduced non-lethal options because it's always been a knock off shooter, and the stealth shooters in 2014 during Sniper 3's release all had non-lethal. Back when V2 came out, Nazi zombies were a huge deal so they made a Nazi zombies mode. To my knowledge there isn't really any effect on the game other than making it harder, it's a difficulty challenge.
Idk, the sniper elite guys make really fun gameplay loops but can't seem to make anything else. The levels and AI have always been kinda designed like shit.