@Kieran
Yes, you can assign Custom MIDI messages to any SoftKey and these can be note on/off’s if you wish.
You can even have different ones for press and release, say for example with your GO message, it could be actioned on release just in case someone gets excited and presses it a little early…
(As you don’t have the console to hand, you can see this in Director – https://www.allen-heath.com/dlive-home/dlive-director/ )
Cheers,
Keith.
EDIT: There is no direct USB MIDI compatibility though, the messaging would be via the dLive network port.