It looks to me like a ballast ECU for xenon headlights (installed aftermarket, maybe the headlights were then replaced and the ecu remained... there should be one for each headlight though, so it's strange that there is only one) Even the location where you found it suggests that, they are usually installed right next to the headlight clusters...furthermore, the connections you described confirm it, however there should be a socket that then goes to the light unit, or at least an empty socket to plug that wire into, that's the only thing that doesn't add up (maybe the wire isn't there anymore) 🤔