To answer your question about lack of dock and system tray, I use the top left hot corner to snap windows in Activities often, and I launch mostly from the built in Applications menu. Don’t use the dock much. As for system tray, it’s a fairly minimal work computer so I boot it every day, run slack, browser, etc. and I know there’s nothing really on the background. Don’t need an icon for slack, it’s always on my screen. In my GNOME-based work environment it’s either running and I can see it or it’s closed.