Signal’s defaults are pretty good about that. Push notifications are both opt-in and the information they send can be selected by the user. You can have it say “new message” and that’s it. Or the senders name. Or the whole message.
I agree that it’s not intuitive that that’s a leak to most people, but push notifications are kind of wonky how they work.
It’s remarkably difficult to really fuck up freebsd. On Linux, getting boots to fail is easy. FreeBSD is quite a bit more robust in that regard, as the base image isn’t updated piecemeal.