I feel like Book of the New Sun by Gene Wolfe is in this category. It’s definitely based in the far far future, but the narrator is extremely unreliable (and to avoid spoilers, there’s multiple layers of complexity there), there’s a healthy dose of religious symbolism and mysticism, the author also employs old english words for far future concepts, and the society of that far future has traces of feudalism about, that it really seems like an eclectic mix of fantasy and science fiction.