Your rephrase is not very good. The word "what" is used to introduce a comparison.
Student or Learner
These are sentences from Stephen King's Dreamcatcher.
Barry is an eating machine. And his memory, on this subject, at least, is eidetic. He is to food what Henry's old friend Pete is to directions and geography.
Can I ask your help in understanding how the what connects the back and forth sentences?
Could it be perhaps rephrased like "He is to food as much as Pete is to direction and geography." ?
Thank you in advance.
Barry's passion for food is as much as Pete's passion for directions and geography.
not a teacher