You can invite team members to your workspace in the API Designer, and only they will have access (read or read/write) to the APIs in that workspace.

From the API Designer (which is private), you can optionally publish any of your API versions out to api-docs.io, for public consumption. You don't even need to publish your entire API definition out - you can mark which endpoints/models are private versus public. Only the parts of your internal docs marked as public will be published out :).