actually, in my humble understanding, before WinPE (Windows Pre-boot Environment) existed, long, long before, there were already the famous Live-CD or Live-DVD, which allow to taste the operation of a linux operating system before installing it definitively, also allow to perform rescue diagnostic operations and tests on a computer, which is exactly what winpe also allows, although not so freely ;)

Yes, in Ubuntu it gives you the possibility to test the operating system without installing it.