Really cool. There appears to be a bug though where the presets don't always get reloaded on a new file, requiring enabling and disabling the add-on.
Thank you for your feedback!
Update: I've realized this was indeed a bug and fixed it in v1.1.4.
To clarify how the presets work:
Presets are loaded once per Blender session, so reloading them manually isn't necessary. If you're seeing unexpected behavior, feel free to share more details—I'd be happy to help!
Interesting in principle to add strings to shader nodes, but you can't use them since there isn't a way to plug them into an attribute node.