To call the binary blobs on the Pi "GPU drivers" is an understatement. The VC4 is running the full ThreadX operating system. The Pi is closer to a VC4 board with a secondary ARM coprocessor tacked on than it is to an ARM board.
Oh wow, I didn't knew this. Will look into this, thanks.
All the same, is your adversary really going to use this to attack your machine? They'd have to predict a number of things quite in advance, as well as sneak an attack into the blob.