Sorry, those are basically two different errors.

The original error was NU1101 ("error NU1101: Unable to find package NAME. No packages exist with this id in source(s): nuget, _nix") for Kaligraphy, Kanvas, Kompression, and Komponent.

CS0246 is from me trying to self-package Komponent, Kaligraphy, and Kanvas to provide the derivation.
(k2Repo in the following is just me trying to set the used src once in flake.nix and passing it to the derivations that way so I don't have to update the used commit info more than once)

{
  packages.x86_64-linux = {
    default = pkgs.callPackage ./package.nix { inherit k2Repo; komponent = self.packages.${system}.komponent; kaligraphy = self.packages.${system}.kaligraphy; kanvas = self.packages.${system}.kanvas; };
    komponent = pkgs.callPackage ./komponent.nix { inherit k2Repo; };
    kaligraphy = pkgs.callPackage ./kaligraphy.nix { inherit k2Repo; komponent = self.packages.${system}.komponent; };
    kanvas = pkgs.callPackage ./kanvas.nix { inherit k2Repo; komponent = self.packages.${system}.komponent; };
  };
};

Oh I forgot to respond to the rest of the post, sorry.

If so, you need to make sure the dependent projects reference the dependencies with PackageReference, and you'll need to make sure the dependencies are built with packNupkg = true, and included in `buildInputs of the dependent derivation.

The derivations for kaligraphy and kanvas both have buildInputs = [ komponent ];, and all three have packNupkg = true;, though I'm not 100% sure if they all have PackageReference in the original project, I'll have to look back at that in a bit. I'm assuming that they are correctly doing that, though.

  <ItemGroup>
    <PackageReference Include="Imgui.Forms" Version="1.5.11" />
    <PackageReference Include="Serilog.Sinks.File" Version="6.0.0" />
    <PackageReference Include="System.Drawing.Common" Version="5.0.3" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\..\lib\Konnect.Contract\Konnect.Contract.csproj" />
    <ProjectReference Include="..\..\lib\Konnect\Konnect.csproj" />
    <ProjectReference Include="..\..\lib\Kryptography.Contract\Kryptography.Contract.csproj" />
    <ProjectReference Include="..\..\lib\Kryptography\Kryptography.csproj" />
  </ItemGroup>

This project doesn't seem to use PackageReference for internal stuff, which isn't really surprising. I think you should just make it a single derivation and build the one project you actually want. Kuriimu2.ImGui.csproj?

I've got a couple of .NET 6 EOL PRs if anyone has time to review

• https://github.com/NixOS/nixpkgs/pull/436377
• https://github.com/NixOS/nixpkgs/pull/436407

Yeah, sadly it seems to have failed again

./prep-source-build.sh: line 363:  6047 Segmentation fault         (core dumped) "$dotnetSdk/dotnet" build "$REPO_ROOT/eng/init-detect-binaries.proj" "/p:BinariesMode=Clean" "/p:AllowedBinariesFile=$REPO_ROOT/eng/allowed-sb-binaries.txt" "/p:BinariesPackagesDir=$psbDir" "/bl:artifacts/log/prep-remove-binaries.binlog" "/fileLoggerParameters:LogFile=artifacts/log/prep-remove-binaries.log" "${positional_args[@]}"

I had a go at reproducing this locally, but no luck so far. A core dump would be nice.

$  nix log /nix/store/zcnfwxnbwss3anlqj9wld8mb0w0lp5by-dotnet-vmr-10.0.0-preview.7.drv | rg -i "Phase completed"
unpackPhase completed in 55 seconds
configurePhase completed in 36 seconds
buildPhase completed in 1 hours 20 minutes 17 seconds
installPhase completed in 48 seconds
fixupPhase completed in 3 minutes 21 seconds

It only took just under an hour and a half this time, nice!