Microsoft provides 2 free mini versions of Windows that, while limited to the command line, can still be useful. WinPE can be customized – it’s what the bootable USB sticks are built on that you can create in backup &/or partitioning apps. The Validation OS is lighter weight than WinPE, & can be installed to a device’s hard disk, but comes with fewer built-in apps [e.g., no regedit], & generally won’t run add-in apps like WinPE often can. IMHO it would be more useful for things like moving files around to set a new Windows password [as detailed in an earlier post], where it would be easier to use than trying to run a Command Prompt from Windows setup files.
Unfortunately, you can’t just download WinPE… you must first install Windows ADK with at least the Deployment Tools, install the WinPE add-on [the combo takes up ~2GB], run a simple command to create a WinPE folder, then another simple command to create a bootable USB stick or ISO. That USB stick is essentially Windows boot files plus a boot.wim file.
A .wim file is basically a compressed file archive not all that different from a Zip file. A Windows setup ISO is built around a .wim file that contains all the files Windows needs & uses, while Windows recovery & reset are based on another .wim file that’s more customized to that installed copy of Windows. You can mount a .wim file to open it, and while it’s mounted add software, files, drivers, & even Windows updates – corporate IT may maintain an updated .wim image that they *apply* to every new PC/laptop. And you can do that sort of thing with WinPE’s .wim file too… there’s a large set of add-ons just for that.
The Validation OS OTOH isn’t so evolved… the ISO is basically the OS’s .wim file & not much else. To create a bootable USB stick you 1st create a WinPE USB stick, then swap out the .wim files. You can use apps like Ultra ISO & Power ISO to swap the .wim files in a bootable ISO. To install it you use DISM to apply that .wim, often [usually?] while running WinPE from a USB stick – applying a .wim file means expanding the compressed files it contains & copying them to the folders they need to be in. Applying an image is relatively fast, avoids running / using setup files / routines, but does not do anything with partitions or boot files, which must be dealt with separately.
WinPE can be useful for Windows repairs & maintenance, setting up Windows on *bare metal hardware* [no OS], and sometimes to run apps that don’t have a bootable version, e.g., file recovery apps, though not every app will work – it’s easy to test this using a WinPE ISO with a VM.
docs.microsoft[.]com/en-us/windows-hardware/manufacture/desktop/winpe-create-usb-bootable-drive?view=windows-11
docs.microsoft[.]com/en-us/windows-hardware/manufacture/desktop/validation-os-overview?view=windows-11