With 'mea culpa' for the couple of days delay, today Throne of Eldraine is imported:
https://deckbox.org/editions/543-throne-of-eldraine
The prerelease promos do not include the showcase frames / extended arts, I think that is correct, right?
What do you mean by showcase frames? Im unsure about extended art, but at least with adventure cards you can have the special fancy art version in normal boosters as well. Pulled Goldilocks with special fancy frame art on it in my prerelease. Just FYI.