There's that one AO3 Isekai but it's John Brown and his soul is marching on another world.
The genre kind of sucks, but I keep thinking I should check that one out.
isekai as a format is decently nice, because your protagonist has the same knowledge of the world as the reader, you can just explain shit without it seeming weird
unfortunately it mostly gets leveraged for the wish fulfillment of porn addicts which makes the genre icky
Jonathan Hickman wrote a short comic series called Pax Romana about futuristic mercenaries who perform a coup on a Catholic Church funded mission to go back in time to the 4th century to prevent the East/West split of the Roman empire. It's not great, but one thing I liked is a bunch of non-white characters go "Huh, wait we're not abolishing slavery right away? Fuck that!" and steal nukes and other tech to run away to Africa.
They end up slavers or brainwashing others and essentially making them slaves
