Is there a port for Nordic nRF52840 ?
I don’t think such a port already exists. However, LittlevGL can be ported to any platform that meets the system requirements.
The driver is what you need to implement, just so. reference the nrf52840 SDK example to implement your driver, then provide the driver as callback to lvgl, it’s all.
Nordic have an exemple using Zephyr and the Adafruit 2.8" TFT touch screen. Start with the Nordic Connect SDK if you can. Nordic is going in that direction for futur development. Adapting SPI screen should be relativeli easy Parallel is a lot more difficult, but their is some code on Github using the STM32.