That I wouldn't know. But I know that ZS has push notifications so it's in the code somewhere. Maybe take a look to see how Kieran did it. ZScore also has specific relays in the config so I guess it would make sense to use those to find (most) live events.
It's also better for chat across different apps. In fact, we should have dedicated relays for live events. Every app doing different implementations for something that needs to be standardised and work THE SAME across all apps. The current way - some apps - implemented live events and chats basically just sucks and it's very anti-engagement cause nobody ever knows if they can be seen by everyone else.