This app was mentioned in 1 comment, with an average of 1.00 upvote
I've actually used a bunch of apps and feeds for this exact thing.
Most recently, I paid to subscribe to Safeture (https://play.google.com/store/apps/details?id=com.globalwarningsystem.safetureconsumer). And subsequently cancelled.
And I don't recommend any of them.
They're all too slow.
Twitter, reddit, RSS news feeds, etc, are all between 2 and 10 hours faster than any of these Alert apps.
If you're someone who tosses their phone in their pocket and never looks at it all day. Then they have value. But to anyone who keeps a news app or reddit/twitter at the ready throughout the day, they're worthless.