So XFCe == GNOME and LXDE is GNOME or KDE, depending on which version we're talking about?
UI toolkit doesn't equal a desktop environment. There is tons of stuff in the GNOME ecosystem (some of which it will make a lot of sense for System76 to reuse, no doubt) that can be entirely ignored when you're using GTK to, essentially, draw your UI widgets for you.
UI toolkit doesn't equal a desktop environment. There is tons of stuff in the GNOME ecosystem (some of which it will make a lot of sense for System76 to reuse, no doubt) that can be entirely ignored when you're using GTK to, essentially, draw your UI widgets for you.