As someone who really dislikes the mega-containerization approach and has been unhappy about it since Docker came in with a splash about a decade ago, I'm happy to see a pretty well written criticism of the idea that conatiner systems like Flatpak, Docker, etc are doing a good job of making things easier or more secure for users or devs. They aren't. https://blog.brixit.nl/developers-are-lazy-thus-flatpak/
So here's me speaking favorably about Debian, Arch, Guix, Nix, etc. And all of those can use Guix or Nix as a userspace package manager.
But lord have mercy. Don't use these mega black box systems. You're just accruing a gigabyte sized ball of technical debt for every component in your operating system if you use those.