I saw the following answer answered half of this Q.
Intents in Conversation are similar to NLC. So if you have an existing NLC service, you can export that and import as a CSV file.
Watson Dialog service to Conversation service
After opening the page of Watson NLC Service, no place for the users to export CSV file, then how can we do the above? Many thanks for any tips and thoughts.
I found the answer for my above Q: IBM Watson Cloud Dialog Service cannot export the CSV or Json file for the Watson dialogue. I found the CSV file in the app package. You need to look for this in the app source code package.