Hi! Please note that it's just a change proposition :D
I thought about placing it in theme setting but it didn't feel suitable because in every other editor the grid visibility is placed directly in the editor space. In theme it is possible to change node editor backgrounds for easy differentiation. For example in compositor view I don't really mind grid since backdrop usually covers whole view including grid, as for node view it makes whole view darker and introduces a lot of noise during panning around, especially in editing grouped nodes, possibly causing dizziness.

Placing it in view menu gives us advantages of having more than one node view next to each other and being able to differentiate them at the first glance.
Of course placing it in theme preferences is also a good idea, cause as of now there is no way of tweaking it.

This needs a change in do_versions_theme to ensure existing preferences do not load with grid levels 0. Something like:

if (!USER_VERSION_ATLEAST(283, 6)) {
  btheme->space_node.grid_levels = U_theme_default.space_node.grid_levels;
}

Does this affect the movie clip editor? I guess nah, but the graph/dopesheet view there has a very strong hardcoded grid that could benefit from something like this. 🤔

@ThinkingPolygons (ThinkingPolygons) This change only applies to node based editors