Book rec not directly related to this post: an "intense cross-cultural female friendship is better than guys any day" book that you might not otherwise try if you're not a Trekkie is Star Trek: Dwellers in the Crucible. It features the protagonists as POWs committing mutual self-sacrifice for each other in the name of their intense female friendship, which are themes I think appeal to you. Not much explicit PTSD, but some implicit Stockholm Syndrome at the end which Dr. McCoy bizarrely fails to recognize. Trigger warnings for rape and minor character death.

The protagonists are OCs, and if you skip or skim all the chapters featuring the canonical crew (which is what I do whenever I reread this anyway, even as a Trekkie), I think you can get away with just knowing that Vulcans self-identify as logical (not that I think they in fact are, but humans who write books are notoriously bad at knowing what logic is), Klingons are violent warriors who self-identify as honorable and are at odds with the good guys, and Romulans are a more enigmatic race also at odds with the good guys. Oh, and Vulcans have to mate every seven years or die.

Anyway, I hope I'm not wrong that the important parts of this can be read without too much knowledge of canon, but it occurred to me that it's got a lot of things up your alley, so I thought I'd mention it.