Earlier quoted context omitted.
The solution I use to minimise this is Element One ( https://element.io/element-one ). This is a paid for service that operates bridges from Matrix to Signal, WhatsApp and Telegram. I then get to communicate with all those contacts in one place (I'm on Android so iMessage not a problem). I signed up the moment it came out and they had some teething reliability problems for a while, but it's been great for months now.…
I assume this means the Element One servers have access to the plaintext of my messages?
An alternative is to self host the same set of services.