It looks like a standalone Splatoon Squid Amiibo will be available outside Japan. The product was listed by a dutch retailer and has so far been available only as part of Splatoon game bundle and amiibo 3-pack in Europe and North America.
But it Japan, these Inklings are available as a standalone product. However, a Dutch retailer listing the Squid Amiibo as a standalone product indicates that it will be available in other regions as well. The product is available for €14.98 and will release on November 6, as revealed by the image you see below.
The listing was posted on gamemania.nl. Here’s a look at the standalone Squid Amiibo: