Reddit reviews Benito Mussolini: The First Fascist (Library of World Biography Series)

The major is probably the issue - the one Marxist person I encountered was for a political science undergrad degree.

Anyway, the crux of my point is that scientific racism leads to racial hegemony, not necessarily systemic execution. But Nazism is just the logical conclusion to racial hegemony, where entire subsets of the population become less than fully human. If enacted according to the actual Marxist theory, Marxism eliminates all forms of hegemony. This inherently means the states you refer to as examples of Marxism, aren't Marxist. The post-scarcity utopia is a lie to gain power, and that's why we have terms like Stalinist, Maost, Juche, and so on. Basically, it's very reductionist to say "communism killed more than the Nazis so communism is worse" because there have been more "communist" states, and they're all complete perversions of the actual Marxist theory. It may sound like a No True Scotsman fallacy, but having a nation-state under an authoritarian regime is absolutely antithetical to and mutually exclusive with Marxist ideology.

Now, if those people you encountered think that any of the implementation of "communism" are a shining beacon of human dignity, then I agree that they essentially fall into a category of highschool Che-tshirt-wearing edgelords.

Edit: Also, I do enjoy your analysis of fascism, I don't think I have seen so concise an overview. I had a few classes with A. Cardoza, a historian on fascist Italy and its origins - you might be interested in some of his work. I immediately thought of The First Fascist.