@Hunter B Thanks! That does help a bit.
If I understand correctly, your frontend needs to fetch this dictionary based on their subscription key to render the UI accordingly. Also, your backend would need it to construct SQL queries on the fly.
If that is indeed the case, I would simple suggest storing this dictionary in blob storage and expose an endpoint on your APIM that fetches it for the frontend, and your backend function app would simply fetch (and ideally cache in memory) when a request comes in with a particular subscription key.
Also, if possible, it would be better to use a different format like JSON for the data dictionary as they are better supported by most languages without additional libraries.