Signal is a walled garden and might even leave the EU soon. Of course if that happens, XMPP clients will also be harder to get, but at least I will always have full control over my XMPP server.
The question is - how do you intend to verify whether an application is official or unofficial? What's stopping the official application to be 'patched' with a fake signature feigning validity?
It's very unlikely that performance would be hindered by a particular Linux distribution, but usually rather the desktop environment that it employs. NixOS with LXQt would run very differently to NixOS with GNOME.
yes, it does and its realtime.
personally, I use typst locally, but
the online editor utilises WASM, so if I'm not mistaken, the rendering is real-time and handled by the front-end.