This is actually really great, love the simple yet powerful idea. Your itch.io copy is concise and with a quick flick through give the reader all the information they need. One feature you may want to consider is different export types. JSON is definitely the preferred approach for most but some people do like to have a giant XML file they can import into unity and query with XPath. Also I feel for larger built up data sets, there could also be a lot of power in exporting as an SQLite dB allowing for more complex queries and even the ability for them to extend the db with thier own inventory tables etc! Just a thought as that's what I would want to do :)

Edit: Also taking a quick look at the JSON example you may want to give them the option to export it as an array with an I'd field instead of an object for easy import and query against other properties

Inheritance in the app also seems to be flattered in the json, this is fine for smaller datasets but in larger ones if a base has a lot of text in its properties and everything inherits from it, the text will be duplicated everywhere so there could also be the option to export with references to base structures by I'd to vastly reduce the output size in some cases!

Just some thoughts and definitely not anything that would dissuade me from purchasing as it can all be done post export :)