Virtual Desktopper identifies the current virtual desktop briefly upon switching. It is similar to the "Identify" feature when dealing with more than one physical display. It was designed with instantaneous switching in mind. Running it will automatically disable the system-wide "Show animation in Windows" setting on your machine.
chuckrector/virtual_desktopper
This is a Windows 10 utility that shows the current virtual desktop number when switching between desktops.
CMIT