Yeah, the firmware seems based off of Odroid Go (even the bootloader) with a few changes in implementation. The build process is documented a bit better and the codebase is a bit simpler. The hardware is similar and also open source: https://github.com/pebri86/esplay_micro_hardware
It's a funny coincidence since I was just reading up on the Odroid device.
I like the esplay hardware better- built in audio, and I prefer the horizontal style. It looks like a case design is still a work in progress though. What an impressive thing from one maker!
https://www.hardkernel.com/shop/odroid-go/