I was more seeing if there was a URL I could POST to and get a response in an array or something, but Im looking at the IFVARB website to see where its stored there.
At this time there is no public API or area (besides what you showed in your image) that displays the 3/4-letter abbreviations for VA’s and VO’s. You could always create a GitHub gist with all of this and use a GET response to have all the codes published on a command (like a slash command). Good luck!
There is actually an IFVARB API for Airlines and Watchlist entries. I use it in VANet to validate airlines and Flare to check watchlist status. Contact @Brandon_K to get access.