On looking closer DC socket seems quite possible though I haven’t checked for voltage. Box has no markings on it at all (aside from that logo/pattern) which seems a bit unusual for commercial product. I wonder if it’s a diy job by the previous owner. Just stuck on with a foam pad.
I am looking at one right now in my work cherrypicker. The little hole is to stick a little fob into that’s registered to the driver. It’s a vehicle tracking system called Masternaut. They know where I am, so they can find me and see I’m on STW and not working.
Oh and if the little LED isn’t flashing it’s hopefully disconnected, otherwise someone will know where you are.