you could try to statically link them if the package support it, it does so by using musl

nix build github:NixOS/nixpkgs#pkgsStatic.git

return the pacakge as:

ls -lah git

-r-xr-xr-x 1 rucadi rucadi 5.1M Jan 1 1970 git

ldd git

$ not a dynamic executable

So you don't really need to really grow the container