

The fact that you live here in Australia means I actually have relevant information for once, yay!
I work in individual support through the NDIS. That is the National Disability Insurance Scheme. It has been praised internationally as a wonderful tool for meeting the needs of people without telling them exactly what they have to do. This means it is very flexible and able to meet needs you may not consider, like helping you connect your internet and electricity after moving.
For example, I work with a young autistic person who mostly gets help with dishes, vacuuming, shopping, and dealing with awkward and difficult social issues like returning things to a store for a warranty replacement.
Another people I have worked with just didn’t have the skills to manage dealing with learning to drive. We spent a few weeks of 2 hours twice a week on driving. He got his license and is driving now.
Obviously your needs are unique and honestly there are almost definitely things that you don’t know are needs because it simply has not come up yet, everyone has those. Getting into a situation that is a bit of a stretch for you, something you find challenging but not dire and awful, can be very useful for increasing your skills. If nothing else the challenge of living alone would help you learn about yourself and figure out what you like, what you dislike, what is easy, what is hard, and how to recruit help.
If you have a diagnosis of autism regardless of level you should be able to get some support. If it is level 2 you will get lots and lots of support. The NDIS is absolutely awesome and you can really get tailored support in ways I would not have considered a couple of years ago. Good luck!
I can’t give you any TX specific advice, but for the ADHD related depression and anxiety I can definitely give some advice.
First, CBD oil may be a suitable option. Some is pure enough to not show on a THC test as positive, so that may help. CBD is the part of weed that gives most of the mellow and chill, so it may be enough for him.
Second, depending on his ADHD presentation he may benefit from hard exercise. I find that 5x5 weight lifting is really good, along with some sort of cardio if possible. Lifting heavy things takes a lot of the hyperactive energy away and leaves me clearer.
Third, non stimulant meds. Some people find benefit from things like modafinil and if he could get on that it may provide enough support to quit the weed for long enough to get onto a stimulant.
That said, the USA has really intense laws about stimulant meds as well as a bunch of strange stuff about testing that seems punative. I have meds here in Australia and I have not taken a single test. I know there are online clinics that do ADHD treatment and also there are less than legal methods of getting stimulant meds. I know a couple of people who tried stimulants before getting them prescribed. Maybe that would work for his situation.
As for efficacy, I tried a whole bunch of anti depressant meds, anti anxiety meds, all sorts of stuff, and honestly nothing worked. My k10 was absolutely abysmal and I couldn’t really work. Stimulant meds mean I can work, support my partner, engage in things I enjoy, and live life quite well.
I had to come off my meds for a couple of months while going through a heart valve replacement (unrelated to the meds) and wow, I had forgotten how bad it was without them. They are great, getting the dose and specific stimulant right is important, but yeah, worth every bit of effort. Absolutely life changing.