That concept sounds so good. But then, I do absolutely love "modern socialist winds up in medieval fantasy world, quickly becomes so disgusted (s)he must apply dialectical materialism and drag this place kicking and screaming into a form of communism, 1917 style, after all, tsarist Russia wasn't an industrialized nation either" as a subgenre - I don't like isekai as it usually goes, I do like this variation of it - and I also like less explicitly isekai style dropping a modern communist into a decidedly apolitical or liberal hegemony universe in order to lead a revolution, especially when they didn't set out to do so, and they and the local party's attitude to it is "we want a revolution the way a desperate woman wants an abortion, or the way you want to gnaw your leg off when you've been caught in a bear trap" - the whole "no one wants to need a revolution" trope.

You might like the John Brown Isekai - it's not explicitly communist, he's very much written In Character and less as a revolutionary figure and very explicitly as a Christian acting out of religious conviction against slavery, and an early American who believes in the American style of democracy, but a student of historical communist tactics and governance practice might see some parallels in the military tactics and the very early council systems when they've got less than a hundred people. And, y'know, even a bourgeois revolution is a good thing in a feudal society if it ends slavery and brings some level of democracy. As much as I like stories that take that setting and skip straight to the proletarian revolution. Like the Bolsheviks actually did in our timeline.