Sub initializeUF1(SheetTitle, SelectedFile)
    Dim ws As Variant
    Dim wkb As Workbook
  
        Set wkb = Workbooks.Open(SelectedFile)
                    
    For Each ws In wkb.Sheets
                c00 = c00 & "|" & ws.Name
            Next
            
If SelectedFile <> "" Then
    With Userform1
        .SelectedFile = SelectedFile
        .ComboBox1.List = Split(Mid(c00, 2), "|")
        .Show
     End With
End If

End Sub
With this above code I was able to accomplish what I wanted with the userform, all I need now is to know how to assign the combobox selection to a variable in the main module any thoughts.
This is what I have for in the Userform:
Private Sub CommandButton1_Click()
    Dim SheetTitle As String
    
    SheetTitle = Userform1.ComboBox1.Value
    Userform1.Hide
    
End Sub
Also side-note I really appreciate all the help!