It has years since I ran gnome but I believe that the shell is dependent upon video acceleration. Lacking that, gnome-session was suppose to go into a fallback mode.
OpenBSD Gnome3
A new composting utility has recently been introduced for
gnome-shell and, in current, gnome-shell is a dependency for gnome-session.
In the original post it looks like kde and gnome were tried. My guess is that xfce4 or any of the *****box window managers will work fine.