Ahh I found that I had to ignore the bit about `<labwc_config> and instead have it be:
<?xml version="1.0"?>
<openbox_config xmlns="http://openbox.org/3.4/rc">
<keyboard>
<keybind key="XF86_AudioLowerVolume">
<action name="Execute" command="amixer sset Master 5%-" />
<action name="Execute" command="~/.config/volume_osd.sh" />
</keybind>
<keybind key="XF86_AudioRaiseVolume">
<action name="Execute" command="amixer sset Master 5%+" />
<action name="Execute" command="~/.config/volume_osd.sh" />
</keybind>
<keybind key="XF86_AudioMute">
<action name="Execute" command="amixer sset Master toggle" />
<action name="Execute" command="~/.config/volume_osd.sh" />
</keybind>
<keybind key="XF86_MonBrightnessUp">
<action name="Execute" command="brightnessctl set +10%" />
<action name="Execute" command="~/.config/brightness_osd.sh" />
</keybind>
<keybind key="XF86_MonBrightnessDown">
<action name="Execute" command="brightnessctl set 10%-" />
<action name="Execute" command="~/.config/brightness_osd.sh" />
</keybind>
</keyboard>
</openbox_config>
