On the other hand …
Why does your doctor want you to be this spokesperson? Ask him if he thinks this is going to be good for you, good for your case and therapy, that is, or if it’s because he’s looking for a way to perform outreach, for example, to help others. It may very well be good for you, and bravo if it is. (Although I’m also kind of a hermit and like nothing quite as much as being home alone, I can agree with others that it’s also good to get out more. And if all you do is sit at home to read and watch YouTube, then something that gets you out and about – securely – would probably be a good thing for you. But that’s the key thing: is this being recommended because it’s good for you?)
While I would not ascribe to the doctor any uncharitable or ulterior motives, it is also not completely off the wall to wonder if he wants you to do this because it could reflect well on him. I wouldn’t ask him that, and maybe as well as you know him you can dismiss that thought out of hand – and I’d be happy to hear if that is a ridiculous notion. But people do occasionally use other people for their own ends from time to time, so … it’s worth considering.