There are a small handful of literary magazines with a disability and/or neurodivergent focus. There is a stray writing contest or two. There might be a few grants aimed at disabled artists.
As far as retreats and/or conferences, I have no idea.
Would you find a list of disability/neurodivergence-friendly writing resources helpful? As far as retreats and conferences go, I'm going to be chasing people down online to ask.
If you would find it helpful, could you please let me know what accessibility needs to look like for you? I'm only one person and can only ask questions about the needs I'm personally familiar with.
Also, please share resources you know to be accessible to our community with me so we can have an expansive list!
And ask your friends, too.
The Internet, as far as I know, doesn't have a comprehensive list like this. Maybe someone would benefit...