Great proposal. Would it be possible to track progress somehow? Are you going to work on your fork and how frequently do you think you will PR? If there are some low-hanging fruits suitable for drive-by contributions, I’d like to pitch in.
This proposal could be broken up into multiple pull requests to the main Haddock repository, and tracked using a Github Project.
One important component of the proposal is the removal of GHC-specific stuff from various Haddock modules for which it is not necessary. You could make a drive-by contribution by picking a single Haddock module, and performing a GHC-ectomy.
I’ll ping back when/if the proposal is accepted to coordinate this effort.