Good question!

It is. I contacted a VicRoads approved engineer in regards to this project, and I received the all clear. I've been pulled over by cops, and they were cool with it.

My insurance is ok with it, too.

It does have a software watchdog, and failing that, the gearbox's hydraulics have a safety mechanism that allows for some limited driving.

Almost certainly. Basically all "under the hood" mods like this are— street legality for a vehicle you build or modify yourself is a surprisingly narrow band of requirements that are mostly around safety equipment like lights, horn, etc:

https://en.wikipedia.org/wiki/Street-legal_vehicle

The much higher bars to clear are when it comes to a device that you offer for sale to others for them to operate on the road.