ESP32 and the ST7796S Display chipset

[Comalco]

Hi,
I am hopeful someone may have had some success using the 4inch ST7796S displays using SPI on the ESP32.
I am using a ESP32-WROOM-32U specifically, and some sample code that writes some words an the time from a RTC to a 2inch ST7789 ok.
I believe the 7796 is very similar to the 7789, but having modified Russ Hughes' driver to allow for a 480x320 size and having checked the 7796 datasheet to confirm the used Command opcode values are the same, I don't get any error messages, but I also don't get anything displayed on the 7796.
https://github.com/russhughes/st7789py_mpy
As a relative newbie to Micropython I think I have reached a bit of a dead end. I would appreciate help/pointers from someone more experienced.... TIA.
(I have done several searches and not found any code examples of an ESP32, ST7796 and Micropython thus far).