Here’s an HDD synth project for that very thing I saw the other day! Though probably won’t work for your use case, admittedly. It’s intended for retro systems and goes in an ISA slot, and isn’t available for sale yet anyway.

YouTube video: https://m.youtube.com/watch?v=sASOfpzPjxg

Project page: https://www.strifestreams.com/hddsynth