It would be super to be able to use cabal 3's visibility: public feature (https://fgaz.me/posts/2019-11-14-cabal-multiple-libraries/) on auxiliary libraries. Personally I'd like to make use of this feature to avoid cluttering the write-only namespace on Hackage/Stackage. This is also quite important IMO for backpack due to the number of different libraries required for a backpackized project.

Related: #4910, #2540 and #4564

I couldn't find an existing issue for this, and perhaps this is a better fit for the Stackage repo.