I found a script and modified it to search for a filename in a folder and select the filename.
This code works fine when I use Shell "explorer.exe /select,""" & FilePath & """", vbNormalFocus to open the folder and select the filename. However, it keeps opening a new folder instance instead of using the currently opened folder.
I tried to use this code:

If confirmfolder Then
   Wnd.Visible = True
   oShell.Open FolderPath & ""
   ShellExecute 0, "Select", FilePath, vbNullString, vbNullString, vbNormalFocus

However, it does not select the filename in the folder at all. I’m not sure which part goes wrong, or maybe someone can help with this.

Below is my script.

Dim FolderPath As String
Dim PartialFilename As String
Dim FileFound As String
Dim FileSystem As Object
Dim Folder As Object
Dim File As Object
 
FolderPath = Worksheets("Automation").Range("H3").Value
PartialFilename = Format(Amount, "#,##0.00")


   Set FileSystem = CreateObject("Scripting.FileSystemObject")
   Set Folder = FileSystem.GetFolder(FolderPath)
   For Each File In Folder.Files
       If InStr(1, File.Name, PartialFilename, vbTextCompare) > 0 Then
           FileFound = FolderPath & "" & File.Name
           Call SelectFileInExplorer(FileFound)
           GoTo nextshow
       End If
   Next File
   Set FileSystem = Nothing
   Set Folder = Nothing



 Option Explicit
#If VBA7 And Win64 Then
   Declare PtrSafe Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As LongPtr, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As LongPtr
#Else
   Declare PtrSafe Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As LongPtr
#End If

Sub SelectFileInExplorer(FilePath As String)
   Dim FolderPath As String
   Dim confirmfolder As Boolean
   Dim oShell As Object
   Dim Wnd As Object
   
   FolderPath = Left(FilePath, InStrRev(FilePath, "") - 1)
   confirmfolder = False
   Set oShell = CreateObject("Shell.Application")
   For Each Wnd In oShell.Windows
       If Wnd.Name = "File Explorer" Then
           If Wnd.document.Folder.Self.Path = FolderPath Then
               confirmfolder = True
               Exit For
           End If
       End If
   Next Wnd
   If confirmfolder Then
       Wnd.Visible = True
       oShell.Open FolderPath & ""
       ShellExecute 0, "Select", FilePath, vbNullString, vbNullString, vbNormalFocus
   Else
       Shell "explorer.exe /select,""" & FilePath & """", vbNormalFocus
   End If
End Sub