Assuming jstefanop et. al. get it running on the Orange Pi Zero, the biggest limitation is the storage space; my node is currently using 24G to store the blockchain, so you'll need a sizable SD card.
It could be more practical to store the blockchain on some USB flash stick since there's an USB port available anyway. That way the SD card size wouldn't matter that much and updating the firmware by fully erasing the card content wouldn't reset the blockchain back to zero (or to some other older snapshot the firmware possibly provides).
Yea this is the main issue we are still trying to figure out with the full node (other than the memory limitations we are still working through). We still want to make it that the whole node runs on the current hardware with nothing extra, but based on how bad the node wears down SD cards we might need to provide an external USB drive solution for better reliability.
Almost done with getting Batch 2 out the door, and my full attention will turn to this...