What is this connector? And how to connect audio to my andriod head Unit?

Hi Guys.

I installed the Android head unit in my car. Everything is working. (reverse cam, climate control etc) But when playing songs. It only plays sound from the front end (unsure near dash or just the Android unit). But no sound from the doors.

My Prius is not a JBL one. When looked up online on YT, many suggested connections underneath the front seats. But I don't have such a box in the first place.

I found this stray connector in my car. Is it related to the audio? if yes how to connect it?

Pardon my bare feet. I was cleaning the car and didn't want to wear the shoes without putting in mats.

Attached image link unable to upload the image here.

If this is something please look at the third image as well