1LoadAssembly.cs

            public void LoadAndRun(string file)
            {
                var asm = Assembly.Load(file);

                var DLL_MAIN =
                    asm
                        .GetTypes()
                        .SelectMany(type => type.GetMethods())
                        .First(methodInfo =>
                        {
                            var invariant = methodInfo.Name.ToLowerInvariant();
                            return invariant == dll_main;
                        });

                if (DLL_MAIN == null)
                {
                    throw new ArgumentNullException(nameof(DLL_MAIN));
                }

                DLL_MAIN.Invoke(null, null);
            }

2DirectExport.cs

[DllExport("InitializeMyApp")]
public static void Initialize_MyApp() 
{
    Initialize();
}
private static void Initialize()
{
    // .
}