Perhaps if IG as an organization weren’t so opaque we would have better rules for using it as a customer engagement platform. Personally, I share personal information with companies and organizations once I feel like I can trust them enough to care for that information correctly. It would be neat if IG enabled that in an organized way.
Out of curiosity (real and legitimate curiosity because you brought up the privacy concerns) if you found yourself in the situation I mentioned above — your only platform with successful engagement is Instagram and you want to expand off of the platform — how would you approach it? For example, I would probably try to speak plainly and openly with my IG audience about my problem and how it affects a service that they enjoy and request feedback.