Hi,
Unfortunately our core team do not have the resources here to help people use the open source code version to build custom apps. We provide a service where we can customise the app for anyone who needs it including the Push notifications (Airnotifier) service management. This service helps fund the improvement of the app in general: https://moodle.com/branded-app/
I’d recommend you to check the documentation links that are available in the Forum main page or hopefully somebody else in this forum will be able to help you.
Kind regards,
Dani