Recently, I listened to an episode of the "Security. Cryptography. Whatever." podcast (which you should definitely check out). In that episode, they talked about the inadequate and hilarious security of the Telegram messaging app. That got me digging into different private messaging applications that claim to have end-to-end encryption (e.g. Telegram). Surprisingly, or perhaps unsurprisingly, these applications remain incredibly insecure in most scenarios. For example, while Apple's iMessage claims to be end-to-end encrypted (this means that Apple won't be able to read your messages) if you have iCloud enabled, this immediately becomes moot. Apple's compliance with the EU's Digital Markets Act (and a rumored push for a security backdoor) should be a huge red flag to the world of private messaging.
Perhaps these security concerns are besides the point. What is interesting is that there are currently no ways to test our cryptographic features on a consumer messaging product. This would be really useful for applied cryptography. I'm thinking about creating an End-to-End Encrypted messaging application so that I can test out different encryption standards and compare their efficiency and feasibility in the wild.