There's this thing called receptor complexes (heteromers), where interaction with a particular receptor will indirectly interact with another receptor. CB1 agnoism can apparently crosstalk with 5-HT2A receptors, which may explain it's potential psychedelic effects. Also THC seems to do something with the Glutamatergic system, and i feel from personal experience that once the Glutamatergic system is expanded, that Cannabis can re-activate certain portions of the Glutamatergic system that's been expanded by psychedelics, like it taps you into similar territory. In my experience for a good long while there Cannabis would tap me into the psychedelic space, even feeling like i was coming up on DMT. And it brings out the same level of perception that i get from Aya.
Not saying Cannabis is or should be classified as a classical psychedelic, but it's most certainly psychoactive and has some psychedelic-mimetic effects, ime.
I actually had to quit smoking Cannabis because it started causing me anxiety and paranoia, but also was like a Light plant especially when combined with Rue, like it took the place of DMT as the Light, and it definitely makes me more introspective and teaches me things and shows me a more honest and hard perspective of myself and reality. But, since i've found out about Delta-8-THC which provides a clearheaded high and no anxiety/paranoia, i can smoke/vape that just fine for the most part, and i've found it makes Cannabis a lot more tolerable, so far. I still don't smoke Cannabis but i have taken a few puffs rarely since i quit, just to see, but i have been experimenting with the Delta 8 the last few months, and it's less psychoactive/psychedelic than Delta 9, but still gets me plenty baked.