Let me take this one piece at a time. My answer to your opening question is...both. I do not perceive individual enhancement through advanced technology, on the one hand, and using advanced technology to further the evolution of the whole species as being mutually exclusive.
My comments regarding our intelligence or consciousness eventually merging with that of AI, and thus making us many times smarter, come from reading all of Ray Kurzweil's books, a book by Michio Kaku in which he discusses it, and following Elon's company Neuralink closely, with each iteration of their brain computer interface getting advanced. It may take quite some time, but I do believe that one day such an interface will exist, and then, given that our greatly enhanced intelligence will be able to address the deepest questions in math, physics and the other sciences, the sky will be the limit.
Not sure I agree with you about technology historically making some people smarter and other people dumber, the reason being you are attributing the responsibility of availing oneself of new technology so as to further oneself to the technology. That both makes no sense and I am someone who believes if you want to learn something new, get a new skill set, get a higher paying job, etc., it's up to you to do that.
I enjoyed the touching insouciance of our banter, the almost inflatable swimming pool toy of it all. Sigh...Oh this, oh that...
I know there are a bunch out there. Probably like you, I have seen models that allow disabled people or those suffering from loss of mobility due to neurodegenerative disease to regain some of that function. I remember the very first iteration from Elon's Neuralink being used to do research into neurodegenerative diseases via direct brain stimulation, i.e. applying electrical current to the affected neurons.
The telepathy one was incredible. A woman who was one hundred percent paralyzed, had locked in syndrome, stared intently a computer monitor for a bit, which had what appeared to be a Microsoft Word document open, and then suddenly a perfectly grammatically constructed sentence appeared on the monitor.
Then yesterday, I think, Neuralink came out with another iteration, this one looking like a small sugar cube. Incredibly, in an out-patient procedure, the cube is installed below the skull, above the part of the brain where there is a problem, but not in the brain itself. Again, a man who had lost mobility due to a disease was able to regain a good deal of it this way.