@electron-forge/maker-appx builds .appx packages, which are designed to target the Windows Store.
You can only build the AppX target on Windows machines with the Windows 10 SDK installed.
Configuration options are documented in MakerAppXConfig.
{
name: '@electron-forge/maker-appx',
config: {
publisher: 'CN=developmentca',
devCert: 'C:\\devcert.pfx',
certPass: 'abcd'
}
}