iOS
1. Open Shortcuts App
2. Add New Shortcut
3. Choose Shortcut App
4. Add Action
5. 'Open App'
6. Click to Edit
7. Add to Home Screen
8. Click to Edit Icon and Text
9. Choose Pre-Downloaded Icon
10. Click 'Add'
https://youtu.be/cH66LWWluVE?t=367
Android
Please refer to this guide on setting up custom icons on Android using Nova Launcher.
More detailed set-up instructions to be added.