Note that Rick Strassman is a well known writer on this subject and that his work was, as he stated, nothing but conjecture and not actual fact. He has, in fact, expressed annoyance in the way that the New Age has hijacked his writings and are using them as though they are fact.

"I did my best in the DMT book to differentiate between what is known, and what I was conjecturing about (based upon what is known), regarding certain aspects of DMT dynamics. However, it's amazing how ineffective my efforts seem to have been. So many people write me, or write elsewhere, about DMT, and the pineal, assuming that the things I conjecture about are true. When I was writing the book, I thought I was clear enough, and repeating myself would have gotten tedious. We don't know whether DMT is made in the pineal. I muster a lot of circumstantial evidence supporting a reason to look long and hard at the pineal, but we do not yet know." - Strassman via https://www.erowid.org/chemicals/dmt/dmt_article2.shtml

It is true that the pineal and or parietal glands can form small light sensitive organs in some reptiles. It is called a parietal eye. However it is far less functional than their other eyes and is basically not much more than a crude mass of photosensitive cells.