As far as I know, there's no evidence that endogenous DMT is involved in mystical experiences in any way. I feel like I make this point a lot, but we really have no idea what endogenous DMT is doing in our brains (if it's doing anything, it may be biological white noise). My personal theory is mediating hippocampal-based learning and memory. The visionary effects may be completely coincidental.

Blessings

~ND