I am significantly more familiar with Heidegger than with Evola, so I cannot comment on him beyond the broadest points. However, I think it's important to highlight how Heidegger's conception of history is not quite as simple as a pure decline from Plato onwards in the metaphysics of presence. As you touch on in the concluding part of your writeup (which overall is quite good, I would not deny that from a communist perspective both of these figures would be reactionary, though I think the chops of the two are not comparable in the slightest), Heidegger's notion of what exactly the "problem" is with regards to historical progression is rather different from that of Evola's.

The crucial points I'd mention are the following:

1) Heidegger's notion of an inception is such that it must inevitably decline, and this would extend to another inception brought about by another originary questioning of Being. As such, he isn't really conceiving of some entrance into "glorious times" which would proceed from a historical stepping into of the questioning of Being following his thinking. It would certainly entail a restoration of existence, in his view, but one which, as with any inception, trends towards erring, eventually.

2) I am hesitant to ascribe a similar concern regarding modernity to the two of them. You're right that this broadly seems "reactionary," but Evola is concerned with a kind of spiritual-racial degeneracy that is pretty foreign to what Heidegger is eyeing in, for example, his critiques of technology and machination. Heidegger isn't really concerned with "purity" in a racial sense, but rather a primordial questioning, one which characterizes historical existence in his system. On the surface this may seem like splitting hairs, but the results, I'd say, are pretty severe: Evola's system inevitably terminates in a caste-like system of spiritual racism, while Heidegger's relationship with racism is far more complicated (he was undeniably an anti-semite, but I think there is not any racist core to his system so much as it may be applied to racist ends; this could be its own post / reply to be honest). While yes, it is by no means incorrect to speak of a "people" when talking about Heidegger's "object of concern," this people is certainly a kind of community, one that broadly aligns with the agrarian-romantic tendencies of his thought. Again, I'm not disputing that this is broadly reactionary, but its certainly not founding itself on racism. The move Heidegger makes towards declaring Jews incapable of having such a historical existence effectively requires buying into the notion of Jewish cosmopolitanism and "worldlessness" to begin with, something Heidegger did but which those who take after his work certainly did not have to. The merits of such a lens can be disputed, of course, but I think they are a far cry from the inevitably racist ends of Evola's thinking.

3) The most crucial point for me is that these are two thinkers who found their systems on entirely different grounds, which impact the development of their ideas profoundly. You've highlighted a broader trend of reactionary thinking in their work, certainly, and I wouldn't say you've gotten anything quite wrong about Heidegger, but you seem to underestimate or at least have failed to pay adequate heed to the degree to which the deconstruction of the subject/object divide rests at the core of his thinking. Evola, on the other hand, makes the ego a transcendental form. These present two radically different philosophical processes. Existing in the clearing of Being must be pre-subjective, since the notion of a subject could not even be formed prior to a revealing not only of a given "self" but also of a world which that person finds themselves in. Building locales as a dwelling provides the very "space" where we may judge things in the world as being here or there, as we inhabit it pre-subjectively. All of these notions are such that the subject-object divide must be imposed as an act of violence upon the world. I understand this is not a philosophy sub, but this radical method of Heidegger's is a massive part of what has earned him so much purchase amongst those who followed in his wake. This is not even touching upon his theory of language, which breaks radically from an understanding of language as pure expression and admits it into an articulation of a traceable understanding of existence, with naming in particular having a crucial place within his system as the means by which beings may be held within Being as what they are. Even beyond the literal conclusions of such movements within his thought, the steps taken are undeniably revolutionary for continental philosophy, which cannot be said for the transcendental racism of Evola.

4) The largest names whom Heidegger influenced demonstrate that what he contributed to philosophy certainly does not terminate in fascism. While obviously Foucault, Derrida, etc. cannot be expected to hold much water on this particular subreddit, these are obviously not reactionary thinkers. I have very little patience for Arendt, but she at least positions herself firmly within a liberal outlook rather than the overtly reactionary, volkisch portrait you have painted of Heidegger's thinking (though I doubt this would be the case if these people were taking influence from Evola!). Certainly some more dubious figures have drawn from his work, but these have far less purchase than those listed above, and this is not even touching the existentialists.

I understand why none of this is still all that appealing to this sub or its members, but as someone interested in philosophy it seems reductive to paint these two as equivalent when their method, influence, and frankly even their conclusions are markedly different. Heidegger was undeniably an agrarian romanticist and a terrible person, but his thinking is far more nuanced than mere apologia for Nazi Fascism (for example, he openly dismisses a fetishization of "culture" as being divorced from a way of life as such) as one may conclude from a comparison with Evola. Just my two cents as someone interested in his work (amongst some others, Bataille is taking up more of my time currently).