Our ds had horrendous depression through 6th form. The school was brilliant and arranged counselling, put him on a reduced timetable etc bit ds wouldn't engage, refused to leave his bedroom, didn't attend the counselling or the lessons. He eventually dropped out in Year 13 and then spent the next 6 months in bed. He just wouldn't participate in life or engage with anyone. He was suicidal snd so angry - with us, with the world, with everything.
I honestly couldn't see a future for him. I thought he was unemployable and on a self destruct mission. It was heart breaking but also very difficult for us and for ds2 to live with.
Eventually I insisted that ds1 got a job, any job, just something that would give structure to his days. So he got a part-time, zero hours retail job. The difference we as amazing - within w weeks he became a happy, engaged (and engaging) teenager who was a delight to be with.
After a few months he got himself a proper job in the customer service department of a large organisation. He lovest it. He has also re-engaged with lots of his friends who went to uni. So he has a great social lof especially in uni holidays. But he doesn't regret not going to uni at all.
For ds1, school and an academic career just wasn't working. Whilst I would never say that the answer to all depressed teenagers is to get a job, it certainly worked in our sons case. I think that once the pressure of school and A levels was off the table, he was able to see a future.
I really hope things work out for you and your son OP. 