They actually reverse engineered Apple's iMessage and released a POC. At the time it worked and demonstrated on device bridges being a possibility. The runs locally and then encrypts it client side before it reaches beeper services. This can be enabled for Signal under experimental settings already.

https://blog.beeper.com/2023/12/05/how-beeper-mini-works/

It's a journalist's take, they probably mean that Bleeper doesn't phone home the messages from the client.

Well, now I regret that this comment sounds a bit dismissive, if another reply is true and they run the bridge locally. That's... impressive, and still surprising to think about.

I'd honestly be fine with accepting the compromise of hosted bridges, especially since they seem to offer the ability to self-host the bridges, while using Beepers' Matrix infra. Gives them some extra cred in my book.