On the problem of making rom package. There is no lib file in the system apk?
It shouldn't work. Theoretically, it is possible. Decompress rom. Delete the unwanted apk files in the system\app, put them in your favorite apk files, package them into zip packages, and then brush them in. After startup, the added apk application will be installed. If it doesn't work, no icon will be displayed in APK.