I created a - what I believed to be - bootable GNU-Guix USB. Selected USB as priority startup device. I get a Grub Rescue screen. On that screen I can ls two partitions - hd0, and hd1. I'm certain the hd0 is the USB. The hd0 has a filesystem under it named something like ISO9966. I can enter that filesystem, and see various files, such as 'boot', GNU, etc.
I wish to install Guix alongside Windows 11, in - of course separate - partitions.
I formatted the hard drive in Windows 11, creating an exFAT.
Subsequently -
I repeated the entire process using Rufus from within Windows 11. I used the DD option. I booted with the USB. The boot process completed and the Guix installation process began. I got to a screen/input frame, it says something along the lines of 'no ethernet service available', and a 'try again' button.
It may be that my wireless adapter, which is a - Intel(R) Dual Band Wireless-ac 8260 - isn't supported by Linux-Libre. I'll next research whether it is. I'll either find the correct driver, or I'll attempt to write it myself.