might be very late but as of today ( sun, 19th oct 2025 ) these steps worked for me. I am using electron-builder.

all we have to do is just make a "build/icons" folder and place icons for mac, win and linux.

so

icon.icns - for mac

icon.png - for linux

icon.ico - for window

and run the build command and this will generate the installer icons that you will have on .exe, etc.

thanks