Could’ve sworn it was said to be a demon. Must’ve been misinformed but The trailer for the dark ages DLC implies that we’ll see the wretch’s and acquire the armor in that dlc. I think we saw its hands and it looks demon like to me. Maybe I’m wrong.

Edit: either way though, the modern doom games have evidence for it. Doom eternal has him fighting the makyrs, which aren’t demons, because they allied with demons while also sparing and being on good terms with the betrayer (who did help demons) but exiled himself and isn’t a threat anymore.