I really don't know if we're still talking about Roads Yet Traveled, are we? I'm afraid your ADHD brain and my ASD brain don't make a good pair, haha. Since you brought up the subject of alien devices in human brains, I wonder, what are the chances of Tucker having something similar?
Something is clearly wrong with him; all those hallucinations and numbness aren't normal. Could this be a side effect of his journey through the Mæron?
I'm torn between believing that the Mæron is a teleporter or a time machine, and so I've come to two obvious hypotheses.
Hypothesis A: Tucker was teleported somewhere in the universe with aliens that look like dogs.
Hypothesis B: The Mæron is actually a time machine created at some catastrophic point for humanity and later found by the alien dogs and used by them to bring Tucker to them in the future and then send him back to the past where he would create the machine to be used by the alien dogs and repeat the cycle