I am very interested in this research that has been ongoing for a few years now, and it seems that psilocybin experiences in a clinical setting have been shown to have very positive effects on the mental health of those with terminal diseases. I am not opposed to such uses at all. Here is one example:
Johns Hopkins Study of Psilocybin in Cancer Patient
https://maps.org/other-psychedelic-r...ancer_patients
For point of reference and self-disclosure, I experimented "back in the 70's"
with a bit of this and that, although never to the point that it took over my life or seemed to cause me any harm. I value the experiences, which were lessons on the power of the mind. I am not opposed to some experimentation at certain points in life. But, as you say, that is not Zen practice, which is also "mind eye opening," but also totally down to earth and ordinary in our day to day living. We do not need any mind altering substances apart from Zazen and our practice.
And speaking of the harmful effects of drugs and alcohol ... Trungpa is a case study. I think that he was a sociopath and narcissist (all while teaching lessons on "non-ego"), in addition to being a sex and drug addict. He had some brilliant insights, and he was charismatic, but his behavior did not match the words. His successors in that organization, right down to current times, have exhibited like behavior. I risk violating the Precept on not criticizing other Buddhists in their failings, but I mean to do so as a lesson on what can go wrong in a Buddhist group. The following is worth reading:
https://tricycle.org/trikedaily/enco...dhist-america/
Gassho, J
STLah