As for how it worked out for some of the kids, here are a few stories.
My eldest (NT, average ability) didn't want to do GCSEs, originally planning to go straight into work in an arts-related job. They had a good range of interests. During their teens they self-studied art and other subjects and tried their hand at a number of jobs and voluntary jobs including sports coaching. Their health declined from age 15, and they were eventually diagnosed with Chronic Fatigue Syndrome. By 19 they'd had to give up most sports and hobbies, sticking mainly with art and music. Even part-time work had become impossible. They changed their mind about exams, taking English GCSE at 19 and maths at 20, both of which they found easy though they'd never studied them formally before. Having discovered a passion for animation, they applied to uni despite their lack of qualifications, and had some very good offers based on portfolio. They did their degree part-time over five years, recovered their health, and just graduated at 25. Now looking for a job and quite confident about their prospects of getting something artsy, though probably not in animation.
My youngest (learning disabled, not autistic) wouldn't manage GCSEs. At 19 she is still home educated, learning life skills and academic subjects in an informal way. She does a bit of voluntary work. I plan to encourage her to do some lower-level Functional Skills qualifications to help with employability, but she isn't ready for that yet as she finds any sort of formal study fairly stressful. She's still maturing and gaining basic skills. It's tricky to think of a job which would be a good fit for her, but I do think something is out there! There's no hurry. We aren't on a deadline.
Friend A (PDA) was always obsessively interested in computers, computer games, and computer programming, doing little else from the age of 10, not going out much. He had a couple of friends who shared his interests, and his siblings' many friends were often in the house, so he wasn't isolated. His parents expected that launching him into adulthood would be a long and difficult process. But one day aged about 20, out of the blue he announced that he'd landed a job as a programmer and was starting work soon, asking his mum to help him shop for some suitable clothes. She hid her astonishment and asked whether it was full time. It was. She didn't think he'd last a month. He never looked back. A couple of years later he moved out when he got a new job in a different city, and later acquired a partner. Now about 30 years old, great job, no academic qualifications.
Friend B (PDA) was adamant he would never do anything academic. He liked gaming and was good at organising people, so he vaguely thought he might get a related job one day. When he was 15 his mum managed to persuade him to try a tutor-led home ed GCSE study group, which he loved. It transpired that his reluctance to try anything academic had been due to a fear of failure, which evaporated once he'd had a go and realised he was bright and capable. Before long he was studying for half a dozen GCSEs, applying himself with zeal and excelling academically. He set his sights on a local sixth form, where he did his A levels and then went on to university. I believe he has a good job now, aged 22.
Friend C (PDA) is 16 and declares he will never do anything academic. Though he has no qualifications yet, he's well informed on a wide range of subjects. His interests are decidedly academic, his maturity is developing in leaps and bounds, and I predict he'll go the same way as Friend B. With many unschooled kids it seems like there is a light switch moment when they decide they want something and just work towards it singlemindedly.
Friend D (PDA) did a good set of GCSEs from home a bit later than the usual age, but continued to find daily life and interactions with other people hugely challenging. Somehow I imagined he'd go the same way as A and B, but it turns out that he's always going to need significant practical help throughout the day. I saw him recently and while he's rather more calm and contented than when he was younger, he clearly will never find life easy. He's 21 and does some hobbies.
Friend E (PDA) I don't know as well. His parents are very well off and have said they love having him live with them and will gladly support him indefinitely to do whatever he wants. He mostly does his hobbies, and has a job in a bookshop for a day or two a week. Aged 25, no qualifications. Seems happy.
When I think back to how friends A-D were at the age of 10, (I didn't know E when he was young), they were so frequently deeply distressed and anxious that it was hard to imagine them going on to develop close friendships, relationships, and bright futures. All their parents worked incredibly hard to help them find their way, and nature did its job too!