Hallo,
although I don't know if you are planning to provide a similar SoC
specific "firmware update" option to the arm port of Devuan:
Some days ago I ran Hexxeh's rpi-update script [1] to update kernel and
firmware of the devuan_jessie_1.0.0-beta_armhf_raspi2.img on a
Raspberry Pi 2B.
It pulls and installs kernel, modules, device tree and firmware blobs
from Hexxeh's rpi-firmware repository [2], which claims to be a partial
mirror of the official raspberrypi.org firmware repo.
So far just FYI: It works without issues, at least for my headless rPi.
(You may have to mount the boot partition before running the script.)
Libre Grüße,
Florian
[1]
https://github.com/Hexxeh/rpi-update
[2]
https://github.com/Hexxeh/rpi-firmware