Xamarin (used automatically if specifying a macos tfm like net8.0-macos) stores binaries in the MonoBundle folder which is actually not a valid store for binaries, thus codesign does not sign it and the package can not be notarized.

Additionally, we should allow notarization without code signing. To enable more advanced signing scenarios, we can allow users to pre-sign their app bundle before packing a velopack release. - This might not be possible due to UpdateMac not getting signed.