Thought experiment: "How many US soldiers actually believed in their ideology during the Gulf War?" -- What exactly is "believing in their ideology"? There is a huge range from "doing as you're told" to "believing in your country" in general terms to "believing those at the top know what they are doing" all the way to being absolutely engrossed in the whole thing (although such idealism is hard to sustain when serving at the front).

Also, "at what point"? It's easy to think you're about to do the right thing back in training, but quite different once you're facing reality. Plus, post-war Germany is not exactly a place where WWII veterans were / are encouraged to speak freely. It's probably hard for non-Germans to imagine the degree of cancel culture that took root.

Those who believed -- honestly, or misguidedly -- were shunned as Nazis, those who resisted shunned as traitors, and those who just served shunned as either of the two, depending on the POV of the judging person.

To this day, telling about someone from your family who died serving gets you anything from "he was a hero!" by the neonazis (who you don't want to congratulate you on anything, really) to "good riddance, the swine" from the far left. The best you could hope for is indifference. Which might explain why hard numbers might be difficult to come by.