The GNOME fractional scaling support is part of the 3.32 release so it should also have landed in Ubuntu 19.04. You can enable it in F29/Ubuntu 18.10 but the reason it's not enabled by default is that it doesn't quite work properly.
edit: I just installed Ubuntu 19.04 and it has GNOME 3.32 but there is no fractional scaling available in settings, in either Xorg or Wayland. The old experimental option can still be enabled but continues to make non-GTK3 apps blurry.
The problem then becomes, if you don't have a 200dpi display, the scaling is noticeable.. Just like if you scale the display on a non-Retina monitor on a Mac.
You shouldn't really need to scale 2560x1440 @ 25" unless you have bad eyesight. Go up to a 27 or 30" display.