I spend a lot of time reading through random isekai junk 'cus it's like trashy comfort food for me, but every once in a while I come across a real gem like this. It starts off fairly standard, but the depth of the characters and the world grows quickly and it tackles some pretty unexpected topics, clearly with a lot of research. That said, it does get pretty explanation-heavy and half the heroes are just political and military geniuses for no reason so it can be a bit of a tough read at times, but it is without a doubt very unique.
Also, as a brief aside that won't matter to most people... one of the main characters is a lesbian. Not fanservice, yuri-bait, or the butt of a joke, but a genuinely strong character. She's not a gross stereotype and the fact that she's gay is just one part of her character, rather than her entire personality. As a lesbian myself who has just accepted the straightness of isekai as a universal constant, her presence was a very welcome surprise