I don’t know. Since stack maintainers have shown no interest in improving integration with ghcup, I constantly have to give users support on how to do these things manually: In a ghcup-based setup how to tell stack to use the "recommended" ghc?
I don’t have much capacity these days to deal with these things, so it’s unlikely to improve.
Maybe having added stack support to ghcup was a mistake. But it’s hard to revert that decision now.