StackOverflow is really good for Q&A. It has a reputation system and voting. Questions should absolutely be asked on StackOverflow rather than GitHub. However, to make this work we should hang out on StackOverflow every now and then and answer questions. A nice side effect is you'll get reputation for answering questions there rather than on GitHub.
Comment mentioning the author asking if they plan to provide the additional information. If they don't come back close the issue using `@facebook-github-bot no-reply`.
Valid bug reports with good repro steps are some of the best issues! Thank the author for finding it, explain that React Native is a community project and ask them if they would be up for sending a fix.
Tell the author something like: "Pull requests are welcome. In case you're not up for sending a PR, you should post to [Product Pains](https://productpains.com/product/react-native/?tab=top). It has a voting system and if the feature gets upvoted enough it might get implemented."
This especially includes **new modules** Facebook doesn't use in production. Explain that those modules should be released to npm separately and that everyone will still be able to use the module super easily that way.
When you mention the bot, it follows the commands defined in [IssueCommands.txt](https://github.com/facebook/react-native/blob/master/bots/IssueCommands.txt).