(Note: I am autistic myself)
As a general rule, autistic people like facts. So, what are the facts that make you believe your son can't do all those things? Please, remember that your son has the ability to learn things. So you shouldn't say "it's impossible for him" without even trying.
People often think that "this autistic person will never be able to do that" but they forget that we do learn. And we grow. And people always end up really surprised at how far we can go when the environment is right for us.
Sure, there are things that we won't be able to learn. And other things that we could learn but that would cost us too much (time and energy) so it's not worth it.
Your son has dreams, please don't crush them. People die without dreams or purpose.
According to you, your son wants to "go to university, learn how to drive and move out of home".
Let's take the first item: "go to university".
Is this really what your son wants? Or does he simply wants something linked to that? For example, do he wants the friends and activity that go with university? Does he simply wish to learn more things? Or does he want to study to learn a job and have money?
What makes you believe that your son can't go to university?
Once you found the answer to both those questions, you can find a way to make your son's wish "come true" while avoiding the pitfalls that would make university hard for your son. He could do remote learning. Or learn a job without needing to go to university. Or he could have special adjustments put in place so that he could attend university.
Your son wants to learn to drive. Though, what he probably really wants is to be able to go where ever he wants, whenever he wants.
Does your son know how to ride a bike? If no, start there. If yes, then he can probably learn how to drive a car. Or a cart. Or just an electric scooter (though he doesn't need to know how to ride to be able to use an electric scooter).
Your son wants to "move out of home". This one is both easy and hard.
He is capable of learning, so he is capable of having a job and earning money. Maybe not full time, maybe not without some accommodations. But he could have a job. And if he is too disabled to have a job, he could still have government help who would give him money.
With money, your son can have his own flat and thus, move out.
I am, myself, not able to cook anything. But that's not an issue. I have a job that gives me money which allows me to have food delivered to me each week and then, I just need to microwave it and eat.
I am not really good at cleaning. But I manage. If I did not, I would pay someone to do it for me. As the saying goes, "there is nothing money can't buy".
It's obvious to me that your son wants more autonomy. And you often need money for that. So you should try and find ways for your son to have money. Be it from the government, from a job or simply from you giving him money (and more autonomy).
Now, to really answer your question:
Stop focusing on what you believe your son can't do. Instead, focus on what he can. Start small, be patient, take your time and keep in mind what your son truly wants (eg: more autonomy).
If you see an obstacle, something blocking the way and preventing your son from having what he wants, don't give up. Instead, think harder. Think outside the box. You don't need to make the obstacle disappear. You just need to find a way around it.
Don't believe that something is "impossible". Sure, it might not be possible in the "traditional" way. But it's very likely that it's still doable another way. You just need to use your imagination.
And last but not least: believe in your son. It is much more harder to achieve something when people (especially loved ones) don't believe in you. So please, believe in him.
Figure out what your son really wants. Focus on what he can do. Use your imagination.