UPDATE: I think this project is another great or better option to follow https://github.com/nativefier/nativefier I tested it myself and it's a very good to produce native Windows and Mac desktop apps.
Recently I found this useful app online: https://app.todesktop.com/ It’s capable of compiling a Windows and Mac Installer and open a native window for your app and it’s just great to deliver a custom desktop installer to your client. I think appsheet can make partnership or incorporate this service for whitelabel apps.