For an advanced example of overriding nixpkg and usage of pinning/override layers (ie some mandate or reason to run super old version of grpc) — https://github.

For an advanced example of overriding nixpkg and usage of pinning/override layers (ie some mandate or reason to run super old version of grpc) — https://github.com/digital-asset/daml/blob/master/nix/nixpkgs.nix#L10 https://github.com/digital-asset/daml/blob/master/nix/nixpkg...