Looks like the Admin NodeJS SDK only allows sending messages to device, group and topics. Device group management is not included though. so developers would need to use the the android APIs to do this (https://firebase.google.com/docs/cloud-messaging/android/device-group#managing-device-groups-on-the-app-server). It seems a bit fragmented, so it would be nice if the Admin SDK supports both areas and neatly hides the details.