An interesting question.
I've worked with Paranoid Schizophrenics in a Forensic Mental Health Care Home setting here in the UK.
I was allowed to offer them Mindfulness, but NOT Hypnotherapy / Self Hypnosis...
I could have applied for permission to work with hypnosis with these individuals as long as they weren't in a florid state. But I didn't get around to that as felt the Mindfulness would be enough for now.
I don't know where you are in the World or what the regulations are there, but here are some interesting readings:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436583/#:~:text=Mindfulness meditation alleviates symptoms of,5 and reduced negative symptoms.
Many others here:
My rule of thumb has always been to check with the person prescribing the anti psychotics (and make sure there is a paper trail).
The results to date have varied from indifferent (with permission) to enthusiastic.
With the greatest respect, I would add that I would NOT advise this to people who have no psych-brain training other than Mindfulness.
Hope this helps,