There are a couple in current development you can contribute to. Look at Lemmy and Lobste.rs. There as Prismo too, but it's been discontinued (but you might be able to pick up and fork the code).
It would be cool to be able to sort a comment section, with a dropdown, between "best", "like people I follow", "like /r/askhistorian seeds", "like /r/askscience seeds"