C# in stack object allocation

StackAllocObject.cs

using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

unsafe
{
  var type = typeof(Test);
  var typeHandle = type.TypeHandle.Value;
  var size = Marshal.ReadInt32(typeHandle, 4);
  
  var memory = stackalloc byte[size];
  var pointer = new IntPtr(memory) + 4;
  
  Marshal.WriteIntPtr(pointer, typeHandle);
  
  var instance = Unsafe.As<IntPtr, Test>(ref pointer);
  type.GetConstructor(new Type[0])!.Invoke(instance, new object[0]);
  
  Console.WriteLine(instance.A); // Should be 80085
}

class Test
{
  public int A = 80085;
}