Another way to do true cross-platform Desktop GUI will be leveraging browser on MacOS/Linux/Win, you put your core logic in GO which runs as a local http-server

Another way to do true cross-platform Desktop GUI will be leveraging browser on MacOS/Linux/Win, you put your core logic in GO which runs as a local http-server on your Desktop that talks to your OS underneath, and use browser/html/css/javascript to do the UI. You only need ship the GO binary, users install it and then starting to use your program via a browser.