I’m a little surprised at this: the default “center and zoom” key*, Numpad “.”, centers but does not zoom to selected nodes in the Shader Node. WUWT? 
This one should have been easy. 
Specifically, I’d like it to zoom to a level where the text in the node is the same size (or maybe slightly bigger, but that’s just me) as the text in the rest of the UI.
*sometimes referred to as 'Focus".