I need to create a special account on a computer running Windows 10 Enterprise. This account would launch an application directly on login instead of the default shell and e
I think you set up correctly the custom shell for the user, but maybe you need to activate the ShellLanuncher behaviour. Try this (at the end of your script):
$ShellLauncherClass.SetEnabled($TRUE)
This way the standard windows 10 shell is not launched when you log on with the other account, but (at least in my case) the command line does not start and the result is a black screen.
You can still run the task manager and run a new task from there, but I don't understand why the command line does not automatically start.