the addon should automatically get data whenever the user looks at their auctions and save it somewhere locally

then it will automatically run a loop that will read the json data in the file and hit the api once per hour.

last it will pop up in an ingame message instead of the bot

This isnt going to work. Api calls cant be made in game.

The only option is a helper app that downloads the api call results ok ui reload which may be more annoying than useful.