Dev module notes

This is the development kit:
http://www.orangepi.org/html/hardWare/computerAndMicrocontrollers/details/Orange-Pi-Zero-2.html
https://linux-sunxi.org/images/e/e7/Orange_Pi_Zero2_H616_Schematic_v1.3.pdf
https://linux-sunxi.org/Xunlong_Orange_Pi_Zero2

For this chip:

https://www.lcsc.com/product-detail/Microcontroller-Units-MCUs-MPUs-SOCs_span-style-background-color-ff0-Allwinner-span-Tech-H616_C5365289.html

Here's some Flash mem you can buy for storing our the bootloader:
https://www.mouser.com/c/semiconductors/memory-ics/nor-flash/?memory%20size=16%20Mbit~~256%20Mbit&package%20%2F%20case=SOIC-8&supply%20voltage%20-%20max=1.95%20V~~2%20V&supply%20voltage%20-%20min=1.7%20V&instock=y&active=y&rohscompliant=y&rp=semiconductors%2Fmemory-ics%2Fnor-flash%7C~Memory%20Size%7C~Supply%20Voltage%20-%20Max


You'll probably want 128MBit or more

You need DDR3 RAM. Maybe this:
https://www.digikey.com/en/products/detail/micron-technology-inc/MT41K256M16TW-107-XIT-P-TR/6036700

You probably want to use SPI flash instead of SD cards for storing our actual program data.

You can do that with an SPI flash chip like this:
https://www.digikey.com/en/products/detail/infineon-technologies/S25FL256SAGMFV010/5787626?utm_adgroup=Memory&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Integrated%20Circuits%20%28ICs%29&utm_term=&utm_content=Memory&gclid=CjwKCAjw6IiiBhAOEiwALNqncdw7OFSJN99o_qCy9BuUlcXBTBMOa7n-nbkJKBUm4ny-bv6tAtM5pxoC0ewQAvD_BwE



This is to go from HDMI to 40 pin RGB/LCD:
https://learn.adafruit.com/adafruit-tfp401-hdmi-slash-dvi-decoder-to-40-pin-ttl-display
https://learn.adafruit.com/adafruit-tfp401-hdmi-slash-dvi-decoder-to-40-pin-ttl-display/downloads

Which I believe will allow you to use any of these:
https://www.buydisplay.com/tft-display/tft-display-panel?interface=396
or these:
https://www.crystalfontz.com/c/tft-lcd-displays/interface/dot-clk-interface---generic-rgb/124

Since these run linux you probably want SDMMC4 with microsd internally for storage. Either that or you'll be stacking and programming a lot of flash chips, which doesn't seem realistic. The other option is to try to replace the SD with a single SPI flash module, and run an RTOS like Zephyr instead of linux

You can use the 40pin RPi interface as your standard "CPU slot" of sorts. You plug your ARM module into that. That way you can switch out primary MCUs if we need to. The 40 pin contains standard locations for serial, i2c and spi