VFD displays are simple serial devices and you can literally do "echo 'my text' > /dev/serial-device" to write content to the display in some cases. VGA output will need an app that runs under X11 to output to a second display device, which is quite a bit more complicated.
It's not impossible, but I'm not aware of any existing tools/plugins in the LE ecosystem. Our mid-term technical direction will also see us move from X11 to GBM/V4L2 running directly on the framebuffer so even if you get something working under X11 this will have a short shelf-life in LE.
IMHO dual-display would be easiest to achieve under Windows or a desktop distribution, perhaps with a web-based touch GUI.