Few in this world have done as much for privacy as the people who built Signal. Yes, it’s not perfect, but building security systems with good UX is hard. There are all sorts of tradeoffs and sacrifices one needs to make.
For those interested in the underlying technology, they’re basically combining reproducible builds, remote attestation, and transparency logs. They’re doing the same thing that Apple Private Cloud Compute is doing, and a few others. I call it system transparency, or runtime transparency. Here’s a lighting talk I did last year: https://youtu.be/Lo0gxBWwwQE