Honestly I'm don with dissociatives as the only other class of drug that would come close to being as detrimental for me would be THC. I'd say it's proabbly a toss-up between THC and DXM/Ketamine and relatives. At the low dose which hey give it to people, I'm not sure, but I'll just err on the side of caution.
But, they can certainly be helpful for a sector of people.
Weszface I'm a bit surprised that you don't seem to have heard of the recent trials using NMDA antagonists to alleviate treatment-resistant depression.
I don't think one needs much guidance when consuming NMDA antagonists--that is, unless you consume so much that you shit your pants or something lol.
It's not like psychedelics where you need a trip guide. As far as I'm aware, NMDA trips don't have the potential to cause a "bad trip" like psychedelics might. I haven't done either in quite a long time but as I recall there's sort of a safe, if occasionally poignant, feeling with NMDA antagonists whereas you're basically dumbed down to a child at roughly the same magnitude of dose when one takes a psychedelic, and it can be frankly terrifying.
Honestly, if you live in a country which they're conducting trials with NMDA antagonists and you have treatment-resistant depression without psychosis, you're free to ask if you can participate in a trial.
But this begs the question: what else have you tried? Personally, and I'll never use hallucinogens (including THC) again, I would rather try an NMDA antagonist than get ECT...but ECT is definitely an option if you're treatment-resistant and have tried enough medications (I'm staying away from both though, I value my memory).
I've gone through basically the ringer in terms of trying antidepressants.