I know there is the .wav file for Elements 1.1 on the proper page (/firmware) however surfing the git repo, looks like the firmware code hasn’t been updated in a year.
Is that because it uses stuff from Rings, which is still closed source?
Yes, I don’t think you should expect release of source code for Elements which has been back-ported from Rings to be released until the code for Rings itself has been released.