Hi Guys,
Thanks for your excellent support...
I have updated my Big Sur installation to Monterey successfully, using EFI folder given and managed to solve Bluetooth and Wi-Fi issues using tips provided by Jake Lo and David here.
Only issue I have now is my screen mirroring don't work. It shows on button disabled. Please help if someone have any suggestions. I have intel Wi-Fi and Bluetooth card in my Latitude 3400
Thanks in advance.