Unfortunately it doesn't solve a global problem for company apps.
To be available through unlisted app distribution, you first need to be eligible and approved for normal App Store.
If your app is an "enterprise-ish" one, specific to your company needs, you get rejected.
If you apply for the enterprise program, you get rejected if you have less than 100 employees (our customer's case).
If you distribute with ABM, you only get one country to distribute your app into (as we just discovered). :(