how is this possible ???

the windows installation media is based on windows PE but includes the stuffs for the setup.

this program removes these "useless" components and adds useful tools for computer repair and data recovery * to make the things look small and flexible .

it is safe ??

yes it is safe.. if you don't trust the project you can review the source code in the official github repo...

is it usable on mac os/linux ?

no. because the dism and imagex components are not available

i can use it with a windows 7/8 ISO ?

no. because inject into the modified system components that are only compatible with Windows 10 and later

there is a "user friendly" guide ?

there is a video made by me explaining how to use it ... it's a bit old but give it a look, it might help you https://youtu.be/t7lnROpLRCw

what is windows preinstallation environiment ??

https://docs.microsoft.com/it-it/windows-hardware/manufacture/desktop/winpe-intro?view=windows-11

you saved my computer, how can I thank you?

you can just... give a star to my project on Github and subscribe to my Youtube Channel ... if I've been of any help this is the best you can do.

I don't trust the included files or my antivirus has marked them as unsafe.

just use the version 2.00 or 3.1.0 because it uses only windows components