What is connected to this OBD2 connector? Can anyone help me to understand my FJ 2016?

That has got to be the biggest load of BS I've ever heard. Why would you want your car to speed up when another car is approaching from the rear? I see front end collision with the car in front of you written all over it. Do the newer FJ's have BSD? BSD is technically Blind Spot Detection, which is a warning for cars on the side of you in your blind spots. The mirror should also have little yellow warning lights that light up when cars are coming up on the sides of your car. That explanation still doesn't explain the workings of this device since you'd need forward looking radar to prevent a collision with a car in front. Even my previous 2019 Toyota Rav4 never "sped up" while in cruise control unless it was returning to the preset speed once traffic in front of me sped up. Never, and I mean never, did it speed up in response to a car approaching from behind. The best way to know if your FJ has forward looking radar is if the cruise control adapts it's speed to the traffic in front of you on the freeway. Do you know if your FJ has forward looking radar or back up collision warning? Even my older FJ has a detector to see if I'm going to hit something when I back up. Something is getting lost in translation here.

My 2020 Miata has lane departure warning, which sounds above ~40 mph if the driver drifts out of the lane and over the lane markings. Unfortunately it tends to "see" those black tar filled cracks in the road as lane markings if the sun is just right and also sounds a false warning. It also has rear cross traffic alert, which sends out a warning tone when making a low speed turn at an intersection and it detects a close object like a car next to you OR if you're backing up and a pedestrian or car is going by behind you. That system is sensitive and even gripes if it's only a fire hydrant it sees on the corner. Then there's the blind spot monitoring system, BSM, which keeps track of cars on either side of you while driving and lights up those small warning lights in the mirrors. An alert will also sound if you signal to change lanes and another car is too close in that blind spot. All these systems seem to work together in combination too.

It doesn't have a front radar or automatic braking like my Toyota did, nor does it have adaptive cruise control, which was kind of nice when it would reduce the car's speed if you came up on traffic on the freeway. If you left the system engaged, it would then speed back up to the set speed when traffic cleared. It also had automatic braking, so if you either tried to back up into something or approached an obstacle too fast in front of you, it would apply the brakes. The ABS motor was quite loud when it applied the brakes, at least on the RAV. However, it never sped up if some car came up behind me. Can you image the issues that such a system would cause with tailgaters? Would it speed up your car or what?? in response? It doesn't make sense to even create such a system and it shouldn't certainly be called a "safety system". I'd call it a carmagedden system.

Is it possible this is some tracker or remote kill device?

Dear Gawd, what a bunch of idiots, but yeah, that's where we're headed. I also have traffic sign recognition in my Miata MX-5. It "sees" the traffic signs, like speed limit or stop signs and will display them in the gauge cluster as an indication. Most newer cars probably have this since the installation of front camera technology to help operate those safety systems. But the car also relies on a database for local speed zones, which I gather it must pick up from GPS information or from a NAV SD card card plugged into the system, to get the correct speed for a particular area. I already know it's picking up data for local accidents and traffic alerts from somewhere in the ethersphere because that's always current. But many times the databases are out of date or else don't match, so the displayed recommended speed the car thinks I should be going does not match the actual local traffic signage. I've run into this one A LOT. It's mostly in the "I'm going too fast" direction too, like displaying a 30 mph sign in the dash when the local speed limit is clearly 35 mph. Of course it's never the other way around. I think I'm allowed 3 free times to update my car's NAV database, but after that, it costs money. Well whoopie dips! How many people have the tech savvy to even pull out the NAV SD card, go to their computer and download the manufacturers new NAV data from a special site, install it on the card, then put it back in the car? Most probably go the the stealership, who then will happily charge you for the privilege of doing it for you. I'm willing to bet that next up for "control" will be the placement of sensors in the road and a system that keeps your car from going over the speed limit for that road. As if we don't have better ways to spend our tax dollars.