DXM/dextromethorphan (Robitussin Cough Gels)

Its technically a dissociative and NMDA-antagonist, anaesthetic.

DXM can be an amazing agent for inducing what I would term a hard reset, that is dissociating you the f-out to the extent you may be able to reevaluate and see things in a new light. You will need to take care it doesnt react with other ingested substances you take and there are different thresholds (plateaus) that purportedly have distinct characteristics.

The best source is Robitussin Cough Gels, take care it is a single-ingredient product that you are considering trying. Have a pan to throw up in (you will vomit to some extent) and do not trust any farts.

If you have urinary retention, take a super hot bath but be very careful, maybe have someone check in on you. The hot water will relax your muscles and basically force you to have to and be able to get it out. Limit liquid consumption before/during/after to avoid an unduly full bladder

Edit: it might be a secret antidepressant akin to ketamine (similar profile) and the music euphoria is incredible