Server-side only Firebase cloud messaging push

[Ben Cody]

Hello, is there a supported way to send iOS push notifications through FCM (or in-app messaging beta) from an application server only, without a need to install the firebase sdk in the iOS client? I'm looking for a pathway to programmatically upload an APNS cert to a firebase project and send a push notification only using an APNS token, without having to register an installation in firebase. Worst case, is there a REST API for registering an installation of an app from our back end?

Thanks.