There are builds for ubuntu now. They even run an APT repo. https://support.signal.org/hc/en-us/articles/214507138-How-d...

There's been one a couple in the AUR for a long while, too. Signal Desktop is not too bad. The aesthetics are clunky, and it didn't seem to scale well last time I used it, but decent overall.

I've been using Signal for a couple of months. Even though it works it has some quirks (slow to load up on macos, sometimes message lifetimes don't seem to be working, messages taking time to arrive to a second device although both have the application running). WhatsApp was better in that regard, but I'd prefer to use something a little more independent :)

Ah, and will try Keybase soon, although the downside of these switches are that I need to convince people around me to use them too..

There's a signal electron app, so there's definitely a signal "desktop" app on linux if you want it. I use it every day.

There's even a cli client that someone has written: https://github.com/AsamK/signal-cli

I'm using the Flatpak on Fedora: https://beta.flathub.org/apps/details/org.signal.Signal