First, make sure you have the following things:
- Windows 11 ISO file, downloaded from Microsoft website
- Windows 10 bootable USB drive of at least 8GB. This is the USB that will install "Windows 10" into the computer where the core Windows 11 payload is encapsulated by the preflight Windows 10 installer.
- Computer running Windows 10 to use to put the core Windows 11 (the wolf) into the Windows 10 (sheep clothing)
- Navigate to the Windows 11 ISO file on the Windows 10 machine.
- Right click on it and choose Mount.
- Open the mounted ISO image and open the sources folder inside.
- Look for the install.wim file, select it, and press Ctrl + C.
- Connect the bootable Windows 10 USB drive to PC and open it.
- Also, find and open the sources folder inside.
- Press Ctrl + V to paste the install.wim file you’ve copied.
- Click Replace the file in the destination in the pop-up dialog window.
- Reboot your computer into BIOS and enter the boot menu.
- Change the boot device order: adjust your bootable USB drive to be the first option.
- Exit BIOS and save changes.
- Your computer will restart and you’ll be asked to select and install a Windows 11 version. Remember, the installer from the USB drive thinks it is installing Windows 10, but it is actually installing Windows 11 because the source wim file is Windows 11.