Play store requires a home address for app downloads, both for the publisher and any users, so it would allow precise targeting of people if they ask google to disclose the information. No idea why this isn’t published on F-Droid though .

They mean push notifications where you need to store a device identifying URL to push your notifications to.

If traceability is a concern, using the native iOS notifications is not much better, you just move the burden to Apple (which I assume will be more than happy to cooperate, given they're an American corporate), so nothing is really solved.

The only good solution is your own backend which knows nothing and each app installation maintains a permanent WebSocket connection, then you push them to each client.