Using Lightning Out for external apps is beta right now. However considering that using Lightning Out for Visualforce page is allowed in production org therefore technically we can use lightning out for external app as well in production. Kindly let me know is there any technical limitation for not being able to use Lightning Out in production as of now.
Lightning out for visual force is not in beta so you are fine to use it
Lightning out for any app outside salesforce is in beta and technically should not be packaged
You mention VF in your question as a supporting fact so not sure which you are asking about.