First thing I notice is everything is on the wrong side, I bet that applies to the driver and passenger also (bg). The first picture is of a switchover valve (green) and the diagnostic socket (blue). A switchover valve is an electrically controlled vacuum switch.
In the other picture the red is probably the OVP and the blue I don't know except it might just be a connector rail the 5 and 4 refering to screw size.
The last open connector is of the type used for ABS sensors. It is a shielded connection so the signal inside is small and precious. Speed sensors such as ABS and crank shaft use such connections.
Bosch Master, ASE Master, L1
33 years MB technician