To fix audio/sound output, install the galliumos-braswell-configAUR package using the pacman --force parameter.
It is quite worrying that the wiki article you are following contains instructions to use --force rather than provide instruction on how to adjust pulseaudio's configuration.
See also https://bbs.archlinux.org/viewtopic.php … 3#p1728603
Edit:
https://aur.archlinux.org/cgit/aur.git/ … s-braswell
https://aur.archlinux.org/cgit/aur.git/ … -galliumos
package name change?