One psychedelic/psychoactive drug is not like another - not necessarily better or worse, just different. You may well be shocked by the degree of difference; I'd rather not resort to cheesy analogies because they're likely to create unhelpful preconceptions.
If you do experiment, avoid the enthusiast's trap of trying to sample as many different cocktails as you can. Whether it's a maturity or a cultural thing, there are many temptations to 'max out' on the intensity of the experience, which I think are unhelpful.
As for the therapy aspect, it's wiser to dose with an experienced person present who can help you if you feel distressed, but if a therapist is proposing to script the whole trip then it won't really be 'your' trip any more.
Meditation (at least mindfulness meditation) is meant to rid you of inner monologue though. It can be immensely helpful considering depression is often caused by constant negative thoughts.
My perspective : marijuana is a pretty good palliative medicine, and perhaps in high single doses can be used for psychedelics type work, but generally it doesn't have the healing properties for mental health that the classic psychedelics do.
Breathwork < > fitness. Breathwork, specifically Holotropic Breathwork, was developed by an Md as an alternative to LSD psychotherapy after prohibition began.
I'm happy to discuss more privately as I know these things can be very personal.
As far as breathwork, fitness is almost a form of meditation for me so I think there's some overlap. Running and lifting gives a lot of inner monologue and self reflection time.