Niue, a sovereign state in free association with New Zealand, uses two official legal tender currencies. The New Zealand Dollar is the circulation currency for daily transactions, while the government also authorises legal tender coins in the Niue Dollar currency for collector's purposes.
A number of mints issue a large variety of commemorative and collector coins under the authority of Niue. These coins are dedicated to historical or general popular culture themes not related to Niue itself. Many of them are in standard bullion sizes - such as one ounce of gold (abbreviated as 1 oz Au, where "Au" comes from the Latin word for gold, Aurum). Many of these feature famous movie characters.
This coin is part of the first issue of New Zealand Mint's Marvel Classics series featuring characters from Marvel comics, and is dedicated to Captain America.
Captain America is one of the most famous and popular superheroes of the Marvel Cinematic Universe. The character was originally developed by creators Joe Simon and Jack Kirby and was first introduced in the comics in 1941. Captain America, also known as Steve Rogers, is a former soldier in World War II who became an invincible fighter through an experimental super-soldier serum. After the war, the superhero was frozen and only found and unfrozen decades later. He joined the Avengers as one of the founding members in order to continue his mission to defend the world from evil.
The mint says about the coin:
The patriotic Avenger, Captain America features on this fantastically engraved 1 oz gold coin! Displaying a powerful close-up of the hero. Some relief and texture, using sandblasting, further enhance this powerful design.
Officially licensed, this incredibly precious piece is held inside a high-quality coin display case, with an outer box that is custom designed with the same image - creating the perfect package. A Certificate of Authenticity can also be found inside | 
Search for Niue: Gold Ounce 2023 Marvel - Captain America on eBay 