We are using Moodle Mobile app with our customization, now we need to send push notification for all student under specific course, please note that we are using FCM right now but FCM is sending push notification to all users.
So I just want to sent enrolled users on specific course not all the users who are registered on site.
sorry for the delay in answering, it's been some crazy months lately.
Push notifications are usually related to Moodle notifications, so you might want to take a look at how they work and look at message outputs too. As a workaround you could use "bulk messaging" to send a message to all users affected.