lvgl LVGLImport with #include <lvgl/lvgl.h> or #include <lvgl.h>.
Upstream example ported to NuttX is present at examples/lvgldemo.
LVGL can be used with framebuffer device. To find example boards with this preconfigured, search for CONFIG_GRAPHICS_LVGL=y in defconfig files. All of them have also CONFIG_VIDEO_FB=y present.
As a second option, LVGL can talk to a display driver and explicitly draw line by line. For this case, there is no preconfigured board present. Go to Porting section of upstream documentation for more hints.