What I think will happen with BCI data -- like from Kernel or from Neuralink or other companies -- is that they could have a person go into a dark room, and wear a BCI helmet or just use the device implanted in their brain (in the case of Neuralink), and would watch videos, lying down in a comfortable chair, and told, "Try not to move, and just watch the videos." Maybe an eye-tracker could also be added, to keep track of where on the screen they are looking.
They would be shown a large number of different types of videos; hundreds of hours, over many weeks of 1 hour sessions, spaced a few days apart. Some would be movies; some would be scenes from video games; some would be news programs; some would be game shows; some would be TV series; some would be YouTube videos of various sorts; and some might even be videos of robots performing tasks.
The scientists running the project would have a high temporal and spatial resolution scan of the person's brain as they watch. Using Deep Learning, they would build a neural net model that predicts brain responses, given previous brain responses and given the previous frames of video (and maybe also eye-track data).
Once this model is built, they could "show" it some additional videos, and it would generate abstract synthetic brain states that closely match what you would see in the brain of an actual human. Some of these brain states, for instance, might correspond to seeing an error of some kind. This would be useful for monitoring robots -- if some robots make a wrong move, it could be caught and corrected; and the robot could be improved to not make the error again. It could, for instance, make home robots a possibility. If you trained the "brain" on audio data, you could use it to improve virtual assistants, making them a lot more human-like and less brittle.
But... it could also be used to augment a police state: you could use the abstract, synthetic brain to look for criminality 24/7; and you could duplicate it thousands of times -- eyes everywhere, watching everybody.
You could have the brains read over people's emails, listen to their phone calls, looking for any sign of criminality.
Oh, and there is vast and sweeping automation potential, if you can drastically improve the robustness of robots, to where they can work in a wide variety of environments, and can do much more general tasks.