NuGet package for linux and windows alike

I'm using the nuget package net.ibm.data.db2 (->windows), which is also available as net.ibm.data.db2-lnx (->linux).
Now when building my own .Net 6 project MyProj.csproj in VS 2022 using net.ibm.data.db2(or -lnx), I can simply choose which one to use depending on build configuration:

<Choose>
  <When Condition="'$(Configuration)'=='Debug-Linux' OR '$(Configuration)'=='Release-Linux'">
    <ItemGroup>
      <PackageReference Include="net.ibm.data.db2-lnx" Version="6.0.0.200">
        <PrivateAssets>none</PrivateAssets>
      </PackageReference>
    </ItemGroup>
  </When>
  <Otherwise>
    <ItemGroup>
      <PackageReference Include="net.ibm.data.db2" Version="6.0.0.200">
        <PrivateAssets>none</PrivateAssets>
      </PackageReference>
    </ItemGroup>
  </Otherwise>
</Choose>

But when I pack my project it has only one dependency to the chosen build configuration upon packing. Either the windows package or the linux package.

-> If I want to reference this package somewhere else I have to create a package MyProj and MyProj-lnx to let others use my package for windows and linux.

And if they want to create a package, they have to provide a windows and a linux package as well. And so on.

How can I make one package that contains both versions and chooses the right one, depending on build configuration or sth else I can configure? I want to provide one myproj.nupkg for my clients with windows and linux assemblies for build and publish so they don't have to differ or choose anything.

It's ok to assume that all clients got the Debug-Linux and Release-Linux configurations

<!--Based on my research, the APIs in net.ibm.data.db2 and net.ibm.data.db2-lnx should be same. The dll file name also same. The differences between them is they make optimize for windows OS and linux OS.
-->

I notice the dll file name of them are same and the APIs seems also same.

So I have an idea for your requirements. You can based on dll file instead of package manager.

First you can run the nuget command in your project root directory:

nuget install Net.IBM.Data.Db2
nuget install Net.IBM.Data.Db2-lnx

Then add the content you need to the project reference like this:

  <ItemGroup Condition="'$(OS)' == 'Windows_NT'">
	<Reference Include="windows_package_path\IBM.Data.Db2.dll" />
  </ItemGroup>
  <ItemGroup Condition="'$(OS)' == 'Linux'">
	<Reference Include="linux_package_path\IBM.Data.Db2.dll" />
  </ItemGroup>

Property "OS" will get the current System Type, Windows OS will get "Windows_NT", Linux OS will get "Linux".

I resolved my problem by using a nuget package that contains both dlls and copies the right one to the output directory. I do not need to directy reference it, it's only used during runtime.

nugetpkg:
lib -> no file
contentfiles -> both dll files
buildTransitive -> my_copydll.targets

my_copydll.targets contains a condition depending on the used build config ("Release" or "Release-Linux") or the operating system this is being build on. Depending on that, I either copy dll1 or dll2 to the output directory.