And before all you Apple fanbois and fangirls get all hot and bothered about how Apple has better privacy (lmfao), it doesn't. You have the exact same setup on Apple iOS, except it's called APNs (Apple Push Notification service) instead of FCM.
"The delivery of remote notifications involves several key components:
Your company’s server, known as the provider server
Apple Push Notification service (APNs)
The user’s device
Your app running on the user’s device"