They use “uboot-raspberrypi” for the bootloader as mentioned in the OP.
The other kernel that Archlinux ARM provides is “linux-rpi” which is called “RPi Foundation patched Linux kernel and modules”
Here at EnOS, we start with the Archlinux ARM provided image with the “linux-aarch64” kernel. Then we make an image that is used in EnOS. During this process, the “linux-aarch64” kernel is switched out with the “linux-rpi” kernel" and “uboot-raspberrypi” is replaced with
In addition to the kernel and uboot swap, we then add a list of packages that provides a good base for adding a Desktop Manager or Window Manager. Then Calamares is added to the image. This is the image we present to the user.
After installing this image on a uSD or USB SSD, then the first boot loads in openbox and calamares and runs calamares. The user then sets the Time Zone, language, keyboard type, DE or WM, user name, hostname, and passwords. When this is finished, the second reboot yields your full blown EnOS install with your choice of DE or WM.