Hello! We're not sure about what kind of blur on the edges that you've mentioned. We've tested PNG export in the latest build and everything is as sharp as it's intended to be. Most of the strokes are designed to have a gradient color so this might be what's troubling you? If you wanted a more defined outer strokes, you can try the 'Outline' feature in the 'Art Style' sidebar.
As for the DLC, the only DLC available DLC for now is the Christmas Collection Test DLC (which is added just for initial testing on the DLC functionality, so the content is very sparse). It is available for download via the store page or from the itch.io desktop app. Please note that DLC and custom-made contents overall are only available for Pro users.
Hope this helps!