Wait, can you actually do this in Mull (the Android browser)? I'm familiar with this method on desktops, but there are precious few browsers on Android that allow you to export bookmarks. To the best of my knowledge, Firefox, Fennec, Mull etc do not allow this.
In fact, the list of browsers that does allow it seems limited to Chromite and DuckDuckGo, both Chromium forks.