@Candy This is a clone of the Duet3D PanelDue, which we don't support here. Unfortunately the PanelDue is not Open Source (it was not designed in-house by Duet3D) so we don't have any more information on how the hardware is designed.
That said, it sounds like a lot of work to rewrite the firmware to interface the Atmel with an ESP32, particularly when it will limit the display capability (ie, text only). Probably better to find an ESP32 breakout board to connect the ESP and TFT without the Atmel in the middle. Then you could develop a UI in lvgl.io . Look at similar screens from Elecrow or MakerFabs, they're not that expensive.
Ian