With haskell-flake, it's pretty easy to get statically-linked executables. I've got them down to like 20MB with a single Nix stanza.

https://community.flake.parts/haskell-flake/size I actually am not sure if haskell-flake is even needed here? I just learned about this from its docs, but justStaticExecutables looks like an upstream nixpkgs function.