Unfortunately, we are unable to obtain the item. There are some cases where an alternative QI charger has also helped, although it apparently does not work officially. Otherwise, it can also be bought in certain countries from the official store of Google itself: https://store.google.com/us...
However, I see it is currently sold out at Google as well.

Finally, a few Chinese knock-offs can be found on eBay. Not my favourite solution, but currently simply the only one.