My icon is pasted in the App property. But Windows or Linux builds are not showing as in Mac. Not finding any info how to provide my precious app icon to Win or Linx?
To be sure, can you provide screen shots of your application in Finder, Explorer and similar on Linux ?
Also, I suppose you pasted (or drag) your icon here:
Of course, in my macOS applications, I copy the App.icns file at build time instead of the above. I do not tested how this works on other platforms.
Windows you have to assign the icon in the system with an installer.
Edit: that applies to file association icons, sorry!