Hi, that sounds really tough.
Not sure how helpful but wanted to share my experience. My DB was sectioned with psychosis and dx with schizophrenia. Came back to live with parents. Side effects of medication (up all night, binge eating) plus weed habit caused friction. His first social worker was crap but it was agreed that moving out would be best, as he wanted freedom too (he had lived on his own before getting unwell).
Got a flat, got into drugs, I rescued him a few times (literally, I think he would he dead). Eventually got a decent social worker who moved him somewhere better. Today - still unable to work but does have hobbies, things that keep him 'sane', a few friends. Still takes drugs sometimes and is bad with money. Calls on parent a lot for things a 40 year old should really be able to do (lifts, food, ten pounds here and there).
There is a mental health service that he can refer himself into when he needs support which he does once a year or so, usually when he has fallen out with a girl. He has an annual double appointment with his GP to check health, liver, cholestrol etc. I am glad as there is a strong correlation b/ween mental health and risk of diabetes, liver problems etc. DB has high cholestrol at 40 :(
One thing that was helpful for him was doing Recovery College. He trained as a peer support worker and did a few sessions, it gave him a lot of confidence at the time.
I don't know what to suggest in your situation. I only get really involved with DB if its life threatening now e.g. risk of homelessness (such as cleaning his flat to secure his tenancy for 5 years) or violence (involving the police not me directly), for my sanity really (i.e. not getting too involved in his problems- he actually stole from me when I was closer to him which, asides from the money, traumatised me emotionally and dented my trust in people, all of which came to the surface for me recently under lockdown) and for my parents peace of mind.
Rethink run a support group for siblings. The cycle is FOG, fear, obligation, guilt but remember its not your responsibility, ultimately they have to take responsbility. All the info, referrals mean nothing if they don't have the motivation. Be strong in yourself and you can be at your best X