The two companies have collaborated before to create Xbox-themed cookies. There are six custom Xbox cookie designs with one featuring the Xbox logo and additional cookies for each controller button.
The packs will include special codes to unlocked armor packs or vehicle skins based on the cookies. There is an armor in the game that looks like a Spartan dunked in a frozen treat. Sea of Thieves players will get an entire ship skin that is more black than it is white, as well as a vehicle skin that is cookie-like.
A little over 1/3.
The cookies will be available in 22 countries starting this month. The promotion appears to be limited to European markets and it looks like the cookies will be available on January 16th.
This isn't the first time Microsoft has collaborated with another company. Microsoft and Oreo collaborated on a branding exercise in October, which led to the existence of the eople in Microsoft teams. The Clippy- branded Thins were designed to promote breaks from meetings. The Xbox Series X was created by Microsoft.
There is an article about the availability of cookies.