Education context: Push notifications to Android, iOS etc

Hi. I am putting together educational activities within a Code Club context (9 to 11 year olds).
I am exploring ways to send notifications from instructor-provided Raspberry Pi Node-RED devices to participant-provided Android and iOS devices.

Ideally I would like a single app available for both platforms with simple registration and easy connection to the Node-RED instance. Oh, and free for basic, low-volume use.

However, my research so far suggests that:

  1. There is no simple-to-implement cross-platform stack
  2. Implementing even platform-specific solutions requires a lot of set up for each participant's device (e.g. registering for keys)

Any comments or suggestions?

Thanks
Brendon

The simplest way i found is telegram, there is also push bullet. both have api's and node-red nodes.
Telegram make it very simple to set up bots. Once registered, keys can be obtained in app.

Simply :-
Register account.
Set up bot (using botfather).
Set up private chat room .
Add yourself and bot (give rights, admins etc)
Get key from botfather in app.
Enter key in node-red nodes.
Obtain chat id.
You should then be able to receive/send notifications to and from chat.

Most applications will require parental consent or for the parent to own the account.

Thanks for the really comprehensive reply.
Seems perfect for my context.

You should take a look at this thread @dynamicdave posted just a couple hours ago

Thanks! I'll take a look.