pacman 7 sandboxes its downloads with Landlock and fails every database
sync on a kernel without it, which Namespace's AmpereOne arm64 machines
run: "restricting filesystem access failed because Landlock is not
supported by the kernel!". An ISO build there stops at its first
pacman -Sy.
Where /sys/kernel/security/lsm lists no landlock, or cannot be read, a
wrapper in /usr/local/bin runs every pacman in the build container,
pacstrap's included, with --disable-sandbox, the flag pacman provides for
such kernels. Not DisableSandbox in a config: pacman-offline.conf ships
on the ISO.