You can customize the branding of your custom mobile app by uploading your own images as a single .zip file.
The package used in the simplified use case contains the following directories:
common_assets - Contains the icon.svg file, displayed on the desktop, both in Android and iOS devices
ios - Contains the splashlogo.png file, displayed as a splash screen, and the Icon-72.png file displayed on the Mobile tab
Any other directories are not related to custom branding.