Came up with a "solution".
Seems too simple to be correct.

For the code below, one needs a Userform with 3 buttons.

1. Shut down any running PowerPoint.
2. Click on the Create PPT button.
3. After the program creates a PPT session, create a PPT session via the GUI, not using the icon minimized by the code.
4. Click on the Close PPT button.
5. Click on the Bye Bye button.

This code would appear to work for those cases in which my code need not keep a presentation alive. So, if I close all the code's presentations, this method appears to work.

If I have to keep a presentation alive, that should be no problem as I just would not close PowerPoint, just set its object variable = Nothing.

Does this hanky panky solve the problem?
  Option Explicit
	Private appPPT As Powerpoint.Application
	 Private blnNewPPT As Boolean
'	Private MyPrivateName As String
   
  Private Sub btnByeBye_Click()
	Unload Me
End Sub
   
  Private Sub btnClosePPT_Click()
	With appPPT
		If blnNewPPT  Then
			If .Presentations.Count = 0 Then
				 .Quit
				lstActions.AddItem "New instance was Quit."
			Else
				lstActions.AddItem "New instance was NOT Quit."
			End If
		Else
			On Error  Resume Next
			.ActivePresentation.Close
			On Error  GoTo 0
			lstActions.AddItem "Extant instance was not  Quit."
		End If
	End With
	Set appPPT = Nothing
	 lstActions.AddItem "Set instance = Nothing."
	On Error Resume Next
	 lstActions.AddItem Err.Number & ":" & Err.Description
	On Error  GoTo 0
End Sub
   
  Private Sub btnCreatePPT_Click()
	'Get existing instance of  PowerPoint; otherwise create a new one
	On Error Resume Next
	Set  appPPT = GetObject(, "PowerPoint.Application")
	lstActions.AddItem  Err.Number & ":" & Err.Description
	If Err.Number = 0  Then
		blnNewPPT = False
		lstActions.AddItem "Extant instance  is being used."
	Else
		Set appPPT = New  Powerpoint.Application
		blnNewPPT = True
		lstActions.AddItem  "New instance was created."
	End If
	With appPPT
'		 MyPrivateName = "HK" & Now & CDbl(Now)
		.Visible =  True
		.WindowState = ppWindowMinimized
		lstActions.AddItem  "Presentations Count: " & .Presentations.Count
	End With
	On  Error GoTo 0
End Sub