” The difference between ignition off, accessory on, and engine on, is negligible.”
When the engine is off I have a big center display telling me to start the car OR I am in IGN/ACC mode.
Also, after shutting the car off the radio plays but now I have to habit of noting that it shuts off when I open the door to get out.
My Mercedes does the same thing. The dashboard is still on but the display changes when you hit the off button and a Don’t forget your key message pops up. So to actually tell if the car is on or off I just have to look at the dashboard.