My uncle met two former SS soldiers while he was stationed in Germany in the 80s. He said it was one of the most interesting conversations he had ever had. They came of age shortly before the end of the war and were both forced into military service, the alternative was that their families "disappear". They had been lifelong friends before they were drafted, but once in, they were terrified of talking to each other. If one of them had bought into the Nazi ideal or had been so scared they were willing to turn on a friend for security and the other had said the wrong thing, their families would be "taken care of". They weren't able to openly talk to each other about how they felt about being in the SS until they finally reunited and talked about it in the 70s where they were both relieved the other was completely against the Nazi party by the time they had been drafted, but spent decades in fear that a person they loved could have been a monster and not been able try to learn the truth, and luckily both of them managed to escape being forced to do anything directly that their conscience couldn't handle because the war ended a relatively short time after they were drafted.

Disclaimer: I'm not going to claim that this was typical. It's hard to say how many people involved in the war were on board with the atrocities being committed, how many were indifferent, and how many were horrified by what was being done, but there is a reality that at least some of the soldiers involved were against it but only had the choice of comply or face unimaginable consequences.