the brown socket on that head unit is used by the rear screen for the digitally superimposed info, such as volumn, icons, etc.
The blue is for the intelligent parking assist ecu connection (It feeds in the front and side cameras)
the 1st 2 connectors are both for the TV antennas, one at front of car and one at back (in spoiler)
the 3rd connector on the 2nd row is telematics (GBOOK, toyota connect, emergency services - it actually has a usb protocol, so would be interesting if we can reuse this for some other purpose) the 4th socket is the aux video/audio input.
the large socket on the bottom right is actually 2 sockets in one, the 8 pins on the left are the Amplifier connection.