Official site: https://www.iceblock.app/
The CNN article talks a bit more about privacy issues. This bit caught my eye:
It’s only available on iOS because Aaron says the app would have to collect information that could ultimately put users at risk to provide the same experience on Android.
I would like to see some details about this. Perhaps there’s a way to work around that problem, even if it meant publishing on F-Droid instead of Google Play.
From what I’ve been reading on this lately (since this started) on iOS a method exists for a service to send out a list of locations, or references list that exists on device (this can work with date/time triggers as well) that would trigger a notification and the local device itself handles notification of the user so the developer has no idea who has been notified for all they know they just shouted locations out into the void and the on-device location services handles the rest.
https://developer.apple.com/documentation/usernotifications/unlocationnotificationtrigger