Yup, my lib on Build should already expose them and have a dedicated sample too.
https://github.com/ScruffR/ITEADLIB_Nextion/blob/master/firmware/NexGraphing.h
https://github.com/ScruffR/ITEADLIB_Nextion/blob/master/firmware/NexGraphing.cpp
https://github.com/ScruffR/ITEADLIB_Nextion/tree/master/firmware/examples/GraphPrimitives
These are not exposed in the original library and are only drawing commands and no graphical objects (unfortunately).
To have graphical objects that can be manipulated after creation ITEAD would have to supply them as components.