I recently came across https://theam.github.io/tintin/index.html. It took a few minutes to get working (use stack with lts-14.21, have a “synopsis” field in .cabal file), but I really like the aesthetic of the docs, the ease of use (markdown files, latex support, runs Haskell in markdown docs).
The only downside is that it doesn’t seem to be maintained, and doesn’t work for ghc 9.
If the authors are reading this, did they get discouraged from maintaining it because of low adoption, and how hard do they think it would be for me to update it? I’d absolutely love to use it instead of sphinx for the monad-bayes docs that I wrote here, but that library uses ghc 9