usb-keyboard.auto-language.sh

#!/bin/bash
sleep 1
DISPLAY=":0.0"
HOME=/home/zvictor/
XAUTHORITY=$HOME/.Xauthority
export DISPLAY XAUTHORITY HOME
usbkbd_ids=`xinput -list | grep "Keyboard" | awk -F'=' '{print $2}' | cut -c 1-2`
usbkbd_layout="dk"
for ID in $usbkbd_ids; do
    gsettings set org.gnome.settings-daemon.plugins.keyboard active false
    sleep 2
    setxkbmap -device "${ID}" -layout "${usbkbd_layout}"
done

Script to be used along the solution pointed by @Sadi on stackoverflow 1 and stackoverflow 2 to make an extra keyboard have a specific and different layout than the laptop's one.