Distro agnostic packages like flatpaks and appimages have become extremely popular over the past few years, yet they seem to get a lot of dirt thrown on them because they are super bloated (since they bring all their dependencies with them).
NixPkgs are also distro agnostic, but they are about as light as regular system packages (.deb/.rpm/.PKG) all the while having an impressive 80 000 packages in their repos.
I don't get why more people aren't using them, sure they do need some tweaking but so do flatpaks, my main theory is that there are no graphical installer for them and the CLI installer is lacking (no progress bar, no ETA, strange syntax) I'm also scared that there is a downside to them I dont know about.
If you use Nix the imperative way (nix profile blah), you don't need to learn the Nix language at all, or write config files. Installing/removing/upgrading packages is just a single command, similar to other package managers.
Eg:
To search for bat on nixpkgs: nix search nixpkgs bat