My suspicion is you didn't read the article, because the README for this otherwise quite awesome-looking project doesn't mention anything about doing FFTs on a

My suspicion is you didn't read the article, because the README for this otherwise quite awesome-looking project doesn't mention anything about doing FFTs on a $3 microcontroller, like the article author did on their Pi. Then again, if I missed it and you can do those FFTs with this project, that's pretty cool.