No. The publisher of the app is the only one allowed to run push notification servers. The privilege of doing this costs $100/year and you're not allowed to si

No. The publisher of the app is the only one allowed to run push notification servers. The privilege of doing this costs $100/year and you're not allowed to sign other people's keys to allow them to do it. Since most chat apps were maintained by volunteers they're unlikely to have the time to dedicate to running a service like this which means that pretty much have to be paying someone in order to have usable chat apps.