UPDATE 29/11/17 10.20am: There's one final update on the Super Mario Cereal saga, as Nintendo has finally detailed what the cardboard box amiibo will now unlock in Super Mario Odyssey on Nintendo Switch.
As expected, the box's NFC amiibo tag will grant extra coins and hearts in-game - which is the same functionality of other amiibo (except for the trio of Odyessey figurines designed specifically around the game).
So, UK cereal fans, you will not really be missing out. If you did fancy still importing a box, however, the cereal will go on sale across the US from 11th December.
UPDATE 29/11/17 4.00pm: Bad news, breakfast fans. Kellogg's has confirmed its Super Mario Cereal will remain US-exclusive for the time being. There's still no word on what exactly the cardboard boxes' amiibo tag will unlock.
Our dreams have been snapped, crackled and popped.
We can confirm this product is being released in the US but not currently in the UK. We will pass your feedback on! Thanks.— Kellogg’s UK & IRE (@KelloggsUK) November 29, 2017
ORIGINAL STORY 29/11/17 11.45am: Nintendo and Kellogg's are launching a Super Mario breakfast cereal whose box is also an amiibo.
Currently only announced for release in the US, Super Mario Cereal is described as a "mixed berry cereal with marshmallows".
The marshmallows are shaped like ? Boxes, Super Mushrooms and 1-UPs. In other words, it's a Mario-branded Lucky Charms.
But it's the box itself which is of the most interest. The packaging states "this box is a special amiibo" and to "try it with Super Mario Odyssey".
There's no word on what effect scanning the box might have, although other amiibo grant a free power-up when tagged. (Odyssey's three special amiibo unlock their own outfits - hopefully there isn't a Kellogg's cockerel costume hidden in the game's code.)
Amiibo have come in the form of cardboard before, of course. There are several hundred Animal Crossing amiibo cards available for use with various games in that series. It's likely the cereal's cardboard box includes an amiibo tag similar to these.
Nintendo has yet to announce the breakfast product officially, but it has popped up in several places now - on a stockist for US retail giant Target, for example, and on breakfast cereal fan blog Cerealously.net (thanks, Nintendo Life).
We've asked Nintendo UK if there's any chance at release here in Blighty.