I have exactly the same use case with leaderboard syncing.
I have been trying to install NodaTime 3.1.6 in Unity / Visual Studio, but cannot get it to work.
I installed NodaTime via NuGet Package Manager in Visual Studio and wrote a few lines of code to do the time zone conversion. But when I try to build in Unity I get these errors in the Console:
" CS0246: The type or namespace name 'NodaTime' could not be found (are you missing a using directive or an assembly reference?)"
Also tried to install via command line:
> dotnet add Assembly-CSharp.csproj package NodaTime --version 3.1.6
info : Adding PackageReference for package 'NodaTime' into project 'Assembly-CSharp.csproj'.
error: Error while adding package 'NodaTime' to project 'Assembly-CSharp.csproj'. The project does not support adding package references through the add package command.
I am using Unity 2021.3, IL2CPP as backend, and tried both .NET Framework and .NET Standard 2.1. I'd like to be able to build for iOS and Android targets.
What am I missing?