Write an AEM service that uses the JCR API to get the nodes. Place the return set to JSON or XML. Pass back to the client and display in a combobox. See this article that shows how to display JCR data in a front end web site widgets:
Write an AEM service that uses the JCR API to get the nodes. Place the return set to JSON or XML. Pass back to the client and display in a combobox. See this article that shows how to display JCR data in a front end web site widgets: