I've been looking for a way to get the system set icons for paths.
For e.g
/Applications/TextEdit.app
/test.docx
/test/folder
On windows i achieved this by using a C# CLI program to generate Base64 pngs of icons for paths, and then call it synchronously in Node...
Given the path to the file (filePath), just call this:-
NSImage *image = [[NSWorkspace sharedWorkspace] iconForFile:filePath];