Running Drush Launcher on Windows
The error message occurs because the command must be drush.phar and prefaced by the php command. In the same folder as Drush Launcher, you'd have to run php drush.phar to get it to work. Elsewhere, you'd have to run php /path/to/drush.phar (which can be just as, if not more, annoying that vendor/bin/drush).

To get it to work, create a folder called drush.bat in the same folder as drush.phar and include the following two lines of code:

@echo off
php %~dp0\drush.phar %*


This file is executed by the command drush since it is in your PATH and will then execute the proper php command passing the correct parameters. You'll then be able to run drush from anywhere on your computer.