Yes all attribution should be to ShakeAlert and their research partners (USGS + universities), I cite the URL above. Not attributed to "Google" or "Apple", no more than we ascribe JK Rowling's works to her word processor manufacturer.

> More people being notified is more value. Most people don't bother to download an earthquake app, particularly if elderly, or traveling from a non-quake-prone region to a quake-prone region.

There are two separate considerations to cellphone-based Earthquake Early Warning: 1. even a small percent of local people installing the ShakeAlert app give decent coverage to everyone. Remember the USGS already also have fixed (non-cellphone) sensors [https://www.usgs.gov/programs/earthquake-hazards/monitoring] and I expect transit and other govt agencies too, anyone got a links? 2. then cellphones get used to immediately send (opt-in) early warning alerts to all cellphone users (not just users who installed ShakeAlert), freeway alert signs for drivers, transit passengers, etc.