>Callidus Assassins etc>accommodate female demographics using existing 40k loreyes I agree, I would argue that there is actually ample space in existing 40k lore to accommodate LGBT or militarised female empowerment fantasies, (see this image
>>5967885 )
as the previous anon
>>5980088 already mentioned there is obviously Sisters Of Battle, Sisters Of Silence (feminists who examine the historical silencing of women's voices in historical literature will enjoy the imagery of that faction lol) you can have those Dark Eldar gladiator girl warriors alongside Harlequins, Death Jesters, you could also have gangers like House Escher in Necromunda, maybe could do something with recruiting an all female Imperial Guard legion from a House Escher style Forge or Hive World etc but I imagine you could also just exalt Slaanesh more, already sympathetic portrayals of Emperor's Children pink space marines, they are pink and look a bit transgender, or even Tzeentch perhaps for LGBT type themes ("Lord Of Change" etc). So no need for recourse to the lost legions space marine chapters / damnatio memoriae primarchs etc where all the mystery is ruined.
I always imagined warhammer Chaos in the sort of Elric Melnibone sense (just an axis of Law, Chaos etc, no dnd grid dimension of Good vs Evil) Chaos in 40k is the Warp, it is not necessarily evil, just as the space marines themselves or Monodominant Inquisitors on rampant Exterminatus purges could be more "Evil" than coexisting with Chaos etc
Of course the motivation of making the Marvel Superhero Comic Space Marines inclusive to females erases this moral subtlety
40k universe lore was never massively coherent, I remember how I was so enamoured and awestruck with the original Abnett Eisenhorn Inquistor novel trilogy, in particular how inquisitor Eisenhorn had that doomed tragic romance with Elizabeth Bequin (they can never be together! Psyker and Null can never romance...!!) then in the Bequin sequel with the girl Beta clone, Abnett just invents a magic cuff with a switch (look we can turn the Null on and off now) so what was the point of the whole doomed romance lol. In the last 40k novel I read (Vincula Insurgency) Abnett has subjugated his imagination fully to prevailing social justice themes of the day, there is a powerful 1-dimensional authoritative black woman who does nothing except appear important and to whom the Gaunt's Ghosts characters salute endlessly, Rawne who was previously a womaniser apologises for his dating behaviour etc. It is all rather predictable, conformist and unimaginative