I had to switch back to Xfce because my old computer couldn’t take GNOME Xorg + kworker. I finally got the volume keys working through that amixer method, which didn’t require any extra packages by this point because it probably came with alsamixer. Here’s what I used:
amixer -c 0 set PCM 5%-
amixer -c 0 set PCM 5%+
amixer -c 0 set PCM toggle
The first one is for the lower volume button, the second raise volume and the last one is for mute.
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Kentroverted 