I got the score for the Sonata and ...
I'm able to sight read the first and second movements both hands slowly not too many errors. The third movement with RH slowly.
That being said, I can sight read through things that would take a lot of effort to get presentable. Which puts the third movement out of bounds. Also, it doesn't draw me in as the other two movements.
I'll definitely put the Andante on my 'to learn' list. It is gorgeous. Behind that is the first movement. Someday.
It's funny. In some ways attempting such works is my personal version of a marathon. The process is private. One might have a few fans who will enjoy hearing the end result. And that's fine with me.