Reply to Is it possible to include a second app icon to be used on macOS versions prior to 11.0 Big Sur? Just add AppIcon-1016.icns file in the app bundle. See Steve Troughton-Smith's discovery here: twitter.com/stroughtonsmith/status/1278364051572232192 (can't make it a link: "This URL can't be included in your post"…). App & System Services Core OS Aug ’20