It's not a perfect comparison because we benefit slightly by batching messages with the same content when sending to Android devices, and we have some backend features in place to reduce storage usage when the content is the same across many messages.

iOS, however, is still quite challenging at scale since there's no batching mechanism for APNS, so even bandwidth becomes a bottleneck. We do web push too, which requires a lot of CPU cycles to encrypt each payload for its recipient.