Don't see a problem with not having a store page, as long as the game can't be ordered yet and there's no link to one either, so it's obvious. An announcement is an announcement, and with how many complain that they don't know that something's coming on GOG and end up getting it elsewhere, better announce asap and put up the page when you can. Who knows, there may be uncertainties, they might not have received some data from the dev, whatever.