While it may seem that by the time the war was turning around (42 and 43) and that after the failure of Stalingrad/the 6th Army, as well as the Northern African front/Afrika Korps, the war was coming back to the German Third Reich. With all of the bloodshed spread on two fronts, and an obvious need for new soldiers to go out and fight, why didn't the Nazi's use prisoners within the Holocaust?
I don't mean every man, woman, and child be forced to go out, that would be bad strategy. But why didn't they do examinations of each man, and if they were able-bodied, instead of being forced into gas chambers/camps, be suited up to the battlefield? Of course nobody would expect them to last, but why not just be used as meat shields for the "real" soldiers?
If you're not going to train them, then it would be a massive waste of time, transport, and materiel. You would be using up ammunition and equipment that you are already short of, giving it to people who you regard as treacherous and unreliable and incapable of fighting for your country, wasting time and transport capacity getting them into the fight only to be slaughtered because they have no idea how to fight because they haven't been trained.
Much better off using all those resources to outfit trained men who are capable of fighting, and getting them into the fight where they will take part and influence the outcome.
Around 20% of Germany's labor force was slave labor by the end of the war; removing that would cripple the economy.
Source:
The Wages of Destruction by Adam Tooze
Just a guess, but if a Jewish male prisoner of sound mind and good health was given a weapon, I bet he would turn it on a nazi solider the first chance he got. I mean, he is dead either way right? Not to mention the rage factor, for the war crimes committed against his brethren.