It’s out? Or still in development?
Meanwhile the Blip messenging app is available.
And idea developed among others by #[0]
Here you can read about it:
https://bitcoinmagazine.com/business/blip-encrypted-chat-on-bitcoin-lightning
And here you can try it for yourself:
https://play.google.com/store/apps/details?id=com.blipmeapp.
Discussion
Alpha version is out!
It's running on my phone at least, but still seems somewhat alpha-ish