But here's a tip. Trademarks. Everything Cartoon Network makes, even if it's just a pilot, gets trademarks. But when they start to file multiple trademarks, then you know it's something serious. It's how I found out about Mao Mao.
As recently as June 6th they filed a trademark for Bird & Squirrel. That's a book series, it seems, but Cartoon Network is clearly working on a pilot.https://trademarks.justia.com/880/52/bird-and-88052454.html
Knowing the trademark has been filed, I crossreference the name with resume sites like linkedin. See? Somebody working on the Bird & Squirrel pilot.
It may never be released to the public. It probably won't get greenlit into a full show. But if you ever see them file more trademarks for Bird & Squirrel, then you know it's coming.