New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/issues/48876#issuecomment-1962338058

Comment:
It would probably be better to add `/sbin/nologin` to `/etc/shells` than to give the `gdm` user a real shell.

I recommend making the backlight files writable by some particular group (`video` is a common choice) and add `gdm` to that group. This might avoid the privilege escalation entirely and stop pkexec from complaining.