For the product roadmap, see What's the roadmap for Adobe XD?
You can see the current community voted features in priority order on our User Voice site - you’re welcome to add new feature requests and vote on existing ones to influence what we work on as we develop Adobe XD.
Yes, PDF export is high on the backlog. Thanks for letting us know that you need it. What are you exporting to PDF? Is it a series of artboards, or individual 1x assets for iOS?