iznit
Not a hidden file manager. “File Chooser” is not even a full file manager. It is a component of gtk or Qt….. or depending on which program, it might even be a java component. Basically, we do not have a “One Ring To Rule Them all” no single place to apply a style [[[fonts and colors]]] to govern all programs.
If you install a full “desktop environment” [[[mate, or kde or cinnamon…..]]] AND you stick to using only programs installed as part of that desktop environment, then you can have a “One Ring”.