Kevin it looks like you have done a bit with the ODROID GPIO's I've found the pinout for mine and am having a look at making an expansion board to incorporate Dew Heater Control (my old arduino version is documented at www.iceinspace.com.au/63-597-0-0-1-0.html ) and possibly a couple of stepper controllers for Focuser and longer term a rotator. I'm not happy that I understand the limitations (if any) on the GPIO's. I got a surprise as I dug into the GPIO's on the ESP32's and realized how many of them were not really usable for my purposes due to special requirements at boot. So afr I've not found anything for the ODROID that has me convinced that I understand limitations.
I'm thinking of starting a discussion on GPIO usage/resources but trying to workout where it would fit. I found your earlier Waveshare topic but I'm not thinking of just Focusers and Filter Wheels. Thoughts?