Since your FCM tokens are managed by you, you could technically send your own notifications with a pretty simple setup and a bit of configuration. This is just a workaround, but it could help you accomplish what you need.
The idea: Triggering your own push notification method to the onReactionUpdated() listener.
Example in React-Native (but the same principle would apply to iOS and Android):
Setup react-native-firebase (https://rnfirebase.io/messaging/)
Configure your notification payload by grabbing the content you need from the reaction object, which contains the content for your notification payload:
- Set that up as part of your _body payload and call firebase.Notification()
const notification = new firebase.notifications.Notification()
Let me know if this helps. Will be cool to see you implement it!