google cloud messaging - Subscribe a Device Group (notification_key) to a Topic

Question

I've recently encountered this post where the general idea is how to subscribe a user to a topic, with multiple devices. I provided an answer, suggesting to make use of the Device Group, then doing the batchAdd on the server side.

But I was wondering if it was possible to subscribe to a topic using the device group notification_key?

I haven't seen anything that mentions something like that in the docs. The notification key is described in the doc as:

All devices in a group share a common notification key, which is the token that FCM uses to fan out messages to all devices in the group.

So I thought maybe it was possible to use it. But can't find anything that mentions it though. I've looked around the community for any other similar posts, went through the docs, but most of it are just about subscribing a single device to a topic.

Was my answer to the post a good method? Or did I just miss something where there is already a process/flow on how to actually do this?

I haven't really tried it out myself, but it was the only way I could think of. I'm still studying about GCM & FCM and I would appreciate it a lot if someone that tried it before can shed some light about this.

Answer 1

Waitting for answers