/dev/mmcblk0p1 is not mounted on /boot
In the devuan_jessie_1.0.0-beta2_arm64_raspi3.img.xz image, /dev/mmcblk0p1 is not mounted on /boot. Additionally, /boot itself isn't empty. This could lead to confusion for those who want to edit cmdline.txt, config.txt, or upgrade the firmware. I suggest that /boot on the second partition of the sd card be empty, and a line like:
/dev/mmcblk0p1 /boot vfat defaults 0 2
be added to /etc/fstab.