corruptcomputer:

environment = let
  dotnet-sdk = with dotnetCorePackages; combinePackages [ sdk_9_0 sdk_8_0 ];
  dotnetRoot = "${dotnet-sdk}/share/dotnet";
in {
  etc = {
    "dotnet/install\_location".text = dotnetRoot;
  };

  systemPackages = with pkgs; [
    dotnet-sdk
  ];
};

this is what I do in my config: https://github.com/GGG-KILLER/nixos-configs/blob/3553a0247d667bd3d83937e52d63625ba592c1c5/hosts/sora/system/programs/default.nix#L10-L18

corruptcomputer:

environment = let
  dotnet-sdk = with dotnetCorePackages; combinePackages [ sdk_9_0 sdk_8_0 ];
  dotnetRoot = "${dotnet-sdk}/share/dotnet";
in {
  etc = {
    "dotnet/install_location".text = dotnetRoot;
  };

  systemPackages = with pkgs; [
    dotnet-sdk
  ];
};

this is what I do in my config: https://github.com/GGG-KILLER/nixos-configs/blob/3553a0247d667bd3d83937e52d63625ba592c1c5/hosts/sora/system/programs/default.nix#L10-L18