Going back to the idea of the Lovecraft mythos having some sort of reality - the work of Kenneth Grant would be a good place to look, particularly 'Hecate's Fountain' IIRC.
Various stuff on the WWW; this looked quite interesting:
London-based occultist Kenneth Grant has suggested a possible source of Lovecraft’s ideas. He likens Lovecraft’s perception to a faulty lens receiving distorted images; in this case, distorted by Lovecraft’s personal fears and conscious rejection of the information which was transmitted to him in dreams. Grant likens Lovecraft to the notorious British occultist Aleister Crowley, and makes explicit connections between the entities Crowley claimed to have contacted using his own methods of dream control and the entities of Lovecraft’s Cthulhu Mythos. Whilst concrete evidence for this assumption is negligible, interesting comparisons can be drawn from examination of Crowley’s and Lovecraft’s personal attitudes, and it is possible to conclude that had Lovecraft possessed Crowley’s aptitude for magick, he may have presented us with a similar picture to that of Crowley’s New Aeon, or Age of Horus; the age of Force and Fire, in other words, the Nuclear Age.
The reality of the C'thulhu Mythos has correlates as diverse as Hinduism and String Theory. If this universe is indeed Brahma's dream, then the Mythos is the neural architecture of the god being individually self aware and powerful and responsible for the dream, yet utterly alien to the lesser but more complete models of life forms they moderate. String theorists have postulated regulatory intelligences that maintain the rules of nexial brane connections that amount to the same thing. If we are made in god's image, which part of what god?
It’s a testament to any writer that they can create a universe so comprehensive and plausible that people start to think it’s real or based on something real. And when they become an influencing force on other writers that elevates the original work to something with a ‘higher authority,’ and the plausibility continues to thrive.
I wonder too what sort of role Metallica’s Call of Ktulu played in further mystifying Cthulhu mythos. Two types of folks were into Necronomicon it seemed: metal heads and gamers. There is some overlap but the gamers often actually read Lovecraft and had seen that HBO movie Cast a deadly spell.
Yes, I could make the name of the article clickable; I prefer not to do so because copying the text of the post will include the link--that otherwise would be hidden--, and this way people will see it and know they are not being lead to some fishy site. It is a quirk of mine, I always redact posts this way; I use the brackets to avoid punctuation breaking the link.
Regarding Kenneth Grant's approach to the Cthulhu Mythos, he was a big fan of Hans Vaihinger's 1911 book The Philosophy of 'as If '. Which, if studied together with the Typhonian Trilogies, can shed some light on his magickal and philosophical perspective on Lovecraft.
^ I think it's a fine idea. What if it were true . It is becoming more and more likely that he was right about the causative role of consciousness in a quantum universe to explain many of the fringe experiences some people have, not to mention the increasingly expansive reporting of NDEs.. And I haven't taken psilocybin in 30 years.