On boot, the keyboard is set with the udev file /etc/udev/rules.d/g810-led.rules
This file launches the profile stored in /etc/g810-led/profile
To prevent your keyboard flashing 3 times when you reboot use the systemd unit (g810-led-reboot).
A profile looks like this:
# G810-LED Profile (turn all keys on)
a ffffff # Set all keys on
c # Commit changes
More samples can be found in /etc/g810-led/samples.