Using Ketamine as a surgical anaesthetic and giving it to outpatients to self administer nasally are two completely different use cases with different risk profiles.

The risk of abuse and addiction from using ketamine in a surgical setting is incredibly low. That's not necessarily the case (in fact, it definitely isn't) for nasal spray given as a treatment for depression.

Same drug, but completely different use case. It's very well known that it's a physically safe drug, but there is a definite risk of abuse and addiction, as evidenced by the number of people I know with ketamine abuse problems. It's not a drug that should just be given out willy nilly to everyone with depression, in fact a lot of people I know who have problems with ketamine abuse are clinically depressed or have other mental health issues.

Complete agreement from me re: big differences between how we're going to manage this as a post-surgical anesthetic and as an antidepressant.

Not approved to treat depression.

We're not limited by approved FDA indications, although we are (generally) limited by the standard of care. Granted, the current formulation is liquid and intended for IV or IM use (although there is academic literature on mixing ketamine into liquids for oral administration). The liquid part is the fundamental problem with using this off-label, in my opinion.

This doesn't really matter--off-label prescriptions are extremely common and don't seem to be strictly regulated.

You can totally get treated for depression with ketamine already, but the problem is insurance doesn't cover it so it's expensive- several thousand dollars a go, which is not absurd but is beyond most peoples' means. Whereas the hope is an FDA-approved therapy will be covered.