Why a *.pkg generated according to a *.app couldn’t be uploaded to Apple Store via Transpoter on macOS?

On macOS, I made a *.app which is signed, then I used the following commands to generate a *.pkg:

Why a *.pkg generated according to a *.app couldn’t be uploaded to Apple Store via Transpoter on macOS?

On macOS, I made a *.app which is signed, then I used the following commands to generate a *.pkg: