Your ideas seem quite interesting!
I am not sure how well a 40k style sci fantasy setting would work with the design goals of this jam entry. It seems like that could make it hard for the book to feel cohesive.
So I think that's probably not the direction I would like this project to go. But if you have other ideas and would like to still participate in this jam entry, we can try to figure out something that works! Otherwise, I hope you find a group that makes your idea, it sounds cool and I hope to see it as one of the submissions!