The valley is a low bar though. Pho isn’t going to be better in SV for some reason, and a first tier has plenty of mid-high end Japanese options (eg Hatsune’s) that you won’t find in the valley without looking really hard. Even high-end hamburgers in China often taste better than the states because they are using Japanese and Australian recipes (beetroot and egg work on a burger).

No, Asian food isn't going to be much better. It's the Western food that is by a lot.

I doubt that, having lived in the bay area and Beijing. The western food available in the latter was much better.

Shenzhen is a notch above Beijing, so I doubt it would be any worse.