Last coordinated GNOME 3.28.x point release is this week: 3.28.2.
We still have the f28-gnome side target and same drill as usual to get
builds in the megaupdate: build with 'fedpkg build --target f28-gnome'
(or if you accidentally built without it, just do 'koji move-build
f28-updates-candidate f28-gnome yourpackage-1.2.3.fc28') and I'll pick
your build up when submitting the bodhi update later this week.