Hi there @tboat and welcome to the strapi forums.
If you want to update the data in json why not use it in a database, if it’s not complicated it structure it won’t take to make either. If it’s not a collection you can use a component. 
If you wan to update it I would suggest not use a static json file. But if you want to go the path you are saying I would make a route in the API, then read the file and return it.