Hey, so basically API is what you wrote, but I want to specify some things:
1. API is way how cube communicates with phone and application, so it describes the way cube send the data, how it's formatted (json? plaintext? some kind of bytedata?), if it's encrypted, and so on.
2. All the previous cubes APIs were not public and authors of timers reverse engineered them.
3. There are few apps with reversed engineered APIs but much enough to consider it's not really hard task todo so.
4. I don't expect any smartcubes protocols to be heavily-encrypted and compressed, they are not work computers or phones
So, if you wanna make cube api public, all what your programmers must do, is open github project and public in it documentation with base example. But as I said I think the cubeast author will reverse it with not very big effort, so I would not depend on your programming team, and maybe GAN company don't wanna make it open-source, and that's really understandable.