Erich Der Schwarze Teufel ("The Black Devil") Hartmann was the deadliest pilot in the history of aerial warfare and, unfortunately, a Nazi propaganda symbol.
As with Rommel, you need to study the lessons that he teaches carefully and unpack them from not only the propaganda they're packaged in, but the flawed fundamental assumptions of the time.
We have a higher burden of care in excavating these forms of knowledge from their surrounding historical matrices than with most. Here, it's like handling radioactive waste or biohazardous material; you need specific intellectual tooling and protective equipment. To understand Hartmann and his myth without being influenced by them, you need to hold an idea in your head and not believe it.
If it's an idea that says you are racially superior in some way just because of how you look, or if it's even a more insidious idea like the notion that it's OK to kill people who did you no harm because someone in charge told you they were bad people... if it's targeting you, or even marketed at you, that's going to be a tall ask.
With Rommel, for instance, you need to place him in context of the Holocaust - same goes for Hartmann, who was, unfortunately, an unrepentant Nazi until the end. That taints everything that they do and stood for, not just morally but also theoretically and practically.
So, we can study the basic ideas of frontal line penetration and 'blitzkrieg' as rather abstract ideas, but I don't think the total-war aspects of that time are going to recur; Americans, Britons and Germans all exerting the totality of their effort to a declared war fighting over, like, Tobruk doesn't seem like it's a high-probability event to plan for. Eating a gun to appease Hitler is probably also not a leadership lesson from Rommel that's worth passing on - or one that most people mention, when they exalt Rommel for his audacity or strategic leadership.
The very framing of these types of lessons of war makes them inapplicable to modern strategic thinking. Force-on-force situations with thousands, even tens of thousands of people, do occur, and there are limited applications of basic desert war theory like Rommel practiced, but that intensity of effort dedicated to protecting or destroying materiel and people is not a high-probability event for our lifetimes.
We are more likely to be guiding and supporting such efforts, as in Ukraine, than we are to be engaged in them ourselves, I think. So the new way of things is low-intensity conflict and peacetime manipulation and maneuvering for supremacy; a shadowy chess-world of positions and threats and feints, not total-war checkers or Reagan-esque dominoes.
With Hartmann's lessons as an enemy of America, you need to get rid of everything about the totality of the war and the insanity of flying around a place you have never been to, in a plane shooting guns at other people flying around in planes, who are shooting guns at you, for some reason that has to do with international politics and hiding a massive industrialized genocide with human slaughterhouses for Jewish people and racial minorities and "undesirables". You have to remove the superiority myths and the unequal advantages, strip away the utterly nonsensical racial- and gender-superiority notions of the time, isolate it from its supportive environment of wartime myth and propaganda.
Do that, and I think there are things that you can unpack from the lessons of America's greatest enemies - enemies of humanity, really - that are worth learning from, if not to implement them, at least to understand their logic and how to oppose them.
And, I'd move, especially for minorities in America, (like me, hi!) it's a survival skill to understand the strategic logic of fascist and authoritarian regimes.
This is different than a white person quoting a Nazi, I'll put it real baldly like that.
So.
One of the things that Erich Hartmann mentions, in his interviews and stories about him, is, surprisingly, the notion of a "coffee break". As he put it, his chain of decision-making was:
See - Decide - Attack - Reverse, or 'Coffee Break'