No new information on the ADC feature request on Espressif”s forums.
I have started layout of the SSD1332 Breakout PCB. I finished the layout and ordered PCBs from OSHPark. Based on the datasheet for the SSD1332, I can get significantly better performance by using it in one of the 8 bit bus modes. Someone suggested that I look at STM32 processors to drive the display with. I will be considering that option this week.