I found DLLImport part in Grpc.Core.dll using dotPeek.
It doesn't specify the full name of the DLL. ".86.dll" is omitted.
I don't know if this is something like a naming rule for AnyCPU platform.

```csharp
    internal class DllImportsFromSharedLib
    {
      private const string ImportName = "grpc_csharp_ext";

      [DllImport("grpc_csharp_ext")]
      public static extern void grpcsharp_init();

      [DllImport("grpc_csharp_ext")]
      public static extern void grpcsharp_shutdown();
      :
```