The quickest way and arguably easiest is:-
1. Open Bootcamp Assistant and download the Windows Support / Bootcamp Driver pack. Close Bootcamp.
2. Download the patched graphic drivers from Bootcampdrivers website (if in your experience you have found these to be more effective). I choose 2023 / March, for max compatibility.
3. Open the official Windows Support / Bootcamp drivers and navigate to the AMD Driver folder. Overwrite the approved drivers with the patched version (when we install Windows, Bootcamp will install the patched AMD Drivers for us and the Adrenalin drivers will work without messing about in safe mode).
4. Download the Windows 11 ISO (multi version).
5. Download Rufus.
6. While all this downloading is going on buy a license from a reputable licensed vendor. You can obtain licences through educational, work or similar initiatives. Cheap licences may not be valid.
7. Download & install Parallels (Demo/Free), use the downloaded iso to install win so we can run Rufus and install ‘windows go’ on an external m.2 nvme drive.
8. Once installed and booted into Parallels, copy the iso to the user desktop (in windows) but drag Rufus to the shared desktop (Mac/win).
9. Select the usb icon or select usb from the menu and select your usb ssd (I used a usb3 to usbc cable as the enclosure was usbc), a notification should pop up, agree then run Rufus.
10. from Rufus you press alt + f to toggle usb drives (if it doesn’t show up), win to go & select start (choose the option you want then next… Rufus will install win 11 & if you want the matrix effect, turn on log view).
When Rufus is complete, copy the win support folder. To your new portable win 11 drive. Now reboot hold alt, let win set up, it’ll reboot again, hold alt and complete the install. Then, use boot camp driver set up and wait for the drivers to install.
I recommend running driver booster and let it update the drivers as you consider slotting that drive internally or, cloning it to a second drive (WintoUSB is great for converting Window to Go to an internal partition). This is where you want to consider Winclone to make deployable image. So that you can recover all your hard work.
I hope this helps and thanks to MisterAndrew for his insights.