Greenland is not a part of the Schengen agreement. However, the country is covered by the Schengen Information System. Thus, a Schengen passport will not necessarily give access to entering Greenland. Individuals from visa required nations shall state whether or not the visa also should pertain for Greenland, when applying for a Danish visa.
EU-citizens national ID-card cannot be used as an identification document when entering Greenland. A passport is required.
Nordic citizens are not required to bring a passport at departure. An identification document containing a photo will be sufficient according to the pertinent aviation safety rules.
There are no requirements regarding the possession of a medication passport at the arrival to Greenland. However, it is required that you can document that the medication you have brought with you to Greenland is legal in the country. Prescription medicine issued in Denmark will always be legal in Greenland.
For Danish citizens, documentation for your medicine can be obtained under the overview of your prescribed medicine at https://www.sundhed.dk