Maybe think of it in terms of what aspect of Discourse (technically, what model in the Discourse database) comes closest to representing the key elements of a business.
None of these seem to fit:
- post
- topic
- tag
- category
I think a ‘group’ is a good match for a business. Discourse groups have fields for:
- name
- description
- owners
- members
- an (optional) badge that can be used to distinguish group members
- an (optional) email domain that can be used to automatically add users to the group
- an (optional) incoming email address that can be used to message the group on the forum via email
- permissions (that can be used to manage category permissions, etc)
Those fields seem to map to the aspects of a business that you might want to represent on a forum. Discourse also has a “groups directory” and individual group pages. I suspect that the groups directory could become your business directory with little to no custom work.
Obviously, this all depends on your specific use case. If businesses are not a key part of your forum, you might want to take a different approach.