With every release Android makes it harder to have a service running in the background. With the introduction of doze there is no alternative to using FCM. FCM has a privileged service where it is able to wake up the device from doze. A custom push service will never be able to do this.
There might be hacks, but I'd rather take Googles approach than to work around on each and every release.
There might be hacks, but I'd rather take Googles approach than to work around on each and every release.