Special NOTE: My understanding from MSDN, it will validate public structure only, not private. Also, it will attempt to repair.

C# Definition:

using System;

using System.ComponentModel;

using System.Runtime.InteropServices;

    [DllImport("winspool.Drv", EntryPoint = "IsValidDevmodeA", SetLastError = true,
      ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    static extern bool IsValidDevmodeA(IntPtr pDevmode, int DevmodeSize);

    public static bool CheckIsValidDevmodeA(IntPtr ptrDevModeA, int totalByteSize)
    {
      try
      {
    // Calls extern IsValidDevmodeA.
    // totalByteSize could be made optional.
    if (IsValidDevmodeA(ptrDevModeA, totalByteSize))
    {
      return true;
    }
    else
    {
       throw new Win32Exception(Marshal.GetLastWin32Error());
    }
      }
      catch (Exception e)
      {
    throw e;
      }
    }

}

VB Definition:

Structure IsValidDevmodeA
   Public TODO
End Structure

User-Defined Field Types:

C++

BOOL IsValidDevmodeA(

  [in, optional] PDEVMODEA pDevmode,
         size_t    DevmodeSize

);

None.

Notes:

My code is from VS 2022 and using .NET Framework 4.8.1 (newer framework shouldn't change much if at all.)

https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/winspool/nf-winspool-isvaliddevmodea