It makes sense to specify the output device in the get and set scripts.

[lxne]

Module is working great on my RPI4B.

One thing: I do have more than one audio device and therefore the default Respeaker script did not work for me.
I had to specify the output device with -c.
It looks like this:

"RESPEAKER_PLAYBACK": {
        getVolumeScript: "amixer -c seeed2micvoicec -M sget Playback | grep -E -o '[[:digit:]]+%' | head -n 1| sed 's/%//g'", // get 0~100
        setVolumeScript: "amixer -c seeed2micvoicec -M sset Playback #VOLUME#%", // set 0~100
      },

Another thing I stumbled upon is that in the readme the scripts are inside ` and not " (see screenshot).

With ` it is not working on raspberry pi.