[Garkin]

This third party program is possible. But data can be updated only when you are not logged into the game, so it would be inconvenient.

There is no way to read/write external data using the in-game API in real time.
Only way to export data to external application are saved variables, but they are saved only when you close UI. It means when you reload UI or when you log out to the character selection screen.
Reading data is even more difficult - if you want to modify saved variables using the external program, game must not be running or you must be in the character selection screen. If you modify data when you are logged in with character, data won't be loaded and will be automatically overwritten when you close UI. Maybe you can avoid overwritting if you generate data file directly to the addon folder, but you will still need to reload UI in order to update data.