I used GodotPCKExplorer (GitHub). :) I couldn't work with the format, though (.sample rather than .wav/.ogg), so I wasn't able to listen to any of them—though I found a way of converting the .ctex files into PNGs. I only spent a short while on it; I didn't go too deep.
Thank you for your blessing, though...! 😁
For what it's worth, I imagine that a fair number of people (myself included) might be interested in guitar- and piano-only versions which might be easier to interpret and learn: it's beautiful music. (^: