Several years ago I proposed a posterization module for Darktable. There was a fair bit of discussion but it didn’t really take off. Do you think your algorithm / process could produce the sort of results I was looking for, and would still like to see? Here is the discussion - Idea for a new dt module - Posterize
There seems to be too many new ideas for the devs to cope with at present, but I’d be interested to know how easy it might be to implement your processing in Darktable.