I absolutely love Niri. It has a built-in screen capture which is good enough for me. Screensharing works fine from Firefox (which is where I do all of my video conferencing). I stopped using multiple screens a long time ago, but I do occasionally hook my laptop up to my TV, and that works out of the box. Though, for stuff like that, I might log into to a Gnome + PaperWM session simply because I don’t remember how to fiddle with things, and I’m not generally trying to optimize for my workflow when I’m giving a live talk or watching TV.