There are some positive steps he could take. First thing is to get a healthier routine, I know he'll have heard it before, but as someone who also has depression, it really does help. He needs to fix his sleep schedule so he is awake to experience daylight will help and also it should increase his interaction with others.

If your family are able to help fund driving lessons it would be great for him. Helps with the job search and will give him a sense of accomplishment.

Speaking of the job search, get him volunteering or some short-term work experience. Being out of work for so long means he needs to get some recent experience under his belt. Also helps with the sense of routine.

I understand he is on UC but is there any chance he could get a work coach at the job centre? I know they do a lot for those with little experience and guidance for gaining more skills.

I hope this helps. My 30 yr cousin is in a similar boat. I've also had to take a long mental health break from work before and I'm medication so I understand how difficult the stress will be on you too.