Hello Isabel,
Moodle HQ provides a service, via certified Moodle Partners, where the Apps team can customise the app for anyone who needs it including the Push notifications (Airnotifier) service management. This service helps fund the improvement of the Moodle app in general. More information: https://moodle.com/branded-app/, if you have any questions there is a contact form at the end of that page.
Regards,
Isabel Renedo
Moodle Apps Team