FYI: Signal stores all of your messages on your device. If something happens to them there, they’re gone. I’m not saying that justifies an update nuking your messages. Just explaining for anyone who may not understand that. There’s no central database storing your data long term. Which is a feature.
Try FairEmail. It’s the closest thing I’ve found.
True but he’s sparking more interest in FOSS so that’s still a good thing. I doubt his advice is perfect but if it gets more people started onto their own journey it’s a win.