Ah, yes you do have to run a service of some kind to interface with Apple. For example the Matrix project provides Sygnal https://github.com/matrix-org/sygnal

Ah, yes you do have to run a service of some kind to interface with Apple. For example the Matrix project provides Sygnal https://github.com/matrix-org/sygnal https://github.com/matrix-org/sygnal which the owner of a Matrix client can run on their own systems. It's not super resource-intensive if you run it yourself, but I can imagine how a "buy vs build" decision for other apps could easily lead to a $$$ monthly subscription with a specialized 3rd party.