Answer: At the time of me asking this question stack was in a bit of a transition from FP complete to new maintainers. I’m happy to see that @mpilgrem has stepped up and picked up development of stack now.
Continuing the discussion from GHCUp button on www.haskell.org:
I haven’t seen much presence of official stack communication online in recent years. Is (the command line tool) stack still actively developed? I’ve heard about bugs that have been known for years. They don’t have support for backpack and cannot install HLS, and they don’t seem to want to add support for GHCup. Looking at their contributor activity on GitHub shows that the volume of commits and changes is fading since about 2019-2020.
I have once recommended stack to newcomers because it seemed like a more streamlined experience, but now I fear that it is slowly fading out as the competition (cabal and ghcup) are incorporating all of its features. That might be a good thing, but I would at least hope to see some official announcement about the direction of the project.
And of course I don’t want to downplay the achievements of the developers of Stack. Although I wasn’t really around yet, I’ve heard that it was quite a big improvement at the time and it seems to have made Haskell more attractive for industry. And of course stackage will probably still stay relevant, but I want to focus on the command line tool for this discourse topic.