If you want my feeling about Frieren's demon depiction, it's that it isn't about any particular race/ethnicity, but is evidently informed by some underlying element of chauvinism

But what are you basing this claim on besides vague intuition? The Demons in the setting are the chauvinists, their entire society is stractured around elitism and domination, they're not a put upon minority ethnic group

The concept of monsters or even races of monsters is not inherently tied to real world realities concerning race and ethnicity, you need the allusions that actually form that connection to make that claim, and you can make those claims about AOT and some other suss anime, but not Frieren

The allusions that define the Demons of Frieren are those of imperialist Europeans and the deprivations of European nobility, that's why the Demons are always ridiculously dripped out, they're what the rich in the real world want to be, their ideal platonic form

because it's still a pogrom fantasy even if it doesn't correspond to any race and isn't meant to either.

The Demons are the ones committing pogroms, they explicitly genocide the elves because the Demon King ordered it, Frieren is literally a victim of genocide, that's the source of her hatred, her character has more in common with the popular imaginary of a post war Nazi hunter than some Gestapo thug looking for "demon" girls hiding in an attic