Non so se sia corretto ma in questo modo mi ritorna la matrice intera:

codice:
 __declspec(dllexport) int* fnwrapper_intarr()
{
    int* test = new int[3];

    test[0] = 44;
    test[1] = 64;
    test[2] = 56;

    return test;
}
codice:
  Dim myaddress As IntPtr = fnwrapper_intarr()
            Dim result(2) As Byte
           
            Dim tempAddress As Integer = myaddress.ToInt32

            For i As Integer = 0 To 2
                myaddress = New IntPtr(tempAddress)
                Marshal.Copy(myaddress, result, i, 1)
                tempAddress = myaddress.ToInt32 + 4
            Next