This is from Wikipedia:
"Greenland is one of the Overseas Countries and Territories (OCT) of the EU because of its political relations to Denmark in The unity of the Realm also known as the Kingdom of Denmark. As a result, Greenland has some integration with the EU's internal market via association agreements. It is also within the EU's common external tariff but they may charge customs in a non-discriminatory manner. Greenlandic citizens have EU citizenship.[4] OCT nationals can be granted the right to vote for and participate in the election of the European Parliament, subject to the conditions defined by the related member states in compliance with Community law.[5]
Up to 2006, all EU funds to Greenland (then €42.8 million per year) went via the EU–Greenland fishing agreement. Between 2007 and 2013, the EU provided €25 million per year outside of fishing.[6] It has been given aid since it pulled out of the EU (see below) in 1985 to roughly the same amount it was previously receiving in EU structural funds (which it lost the right to receive due to its secession). This amounted to about 7% of Greenland's budget. The amount paid via the fishing agreement was in return for EU vessels fishing in Greenland's waters and to help restructure Greenland's fishing fleet. However, this deal was struck down by the European Court of Auditors, who felt the amount the EU was paying was too high for the quantity of fish caught.[7]"
Greenland is eligible for EU funding. Between 2007 and 2013, the EU allocated approximately €190 million, and between 2014 and 2020, €217.8 million are planned for sustainable development, with focus on education.[12] In 2015, a joint declaration about closer relations between EU and Greenland was signed by Denmark, Greenland and the EU.[13]
In March 2015, the President of the EU Commission, the Prime Minister of Denmark and the Greenland Premier signed 'an umbrella' framework document outlining EU-Greenland relations, a “Joint Declaration on relations between the European Union, on the one hand, and the Government of Greenland and the Government of Denmark, on the other”. By this document, the EU confirms its long lasting links with Greenland and reiterates the geostrategic importance of Greenland for the EU.[14]
The Brexit debate has reignited talk about the EU in Greenland, and there have been calls for the island to rejoin the Union.[15]
en.wikipedia.org/wiki/Greenland European_Union_relations
The OCT is yet another form of EFTA where the EU enters into treaties with hooks that ensure that although these country's are not full members they will conforming with EU regulations down the line when agreements are up for renewal.
Clearly the fishing support from the EU whilst very central to the Greenland economy as it's central industry, is critically important, it is interesting to notice that the EU is less interested in the fish than in the geoscience and geostrategic position of Greenland. There might be some mileage in checking out exactly what Greenland and Denmark have signed up to with the EU.
There is something else significant here also, that since Brexit, the EU is encouraging Greenland to become a full member again, I wonder why, could it be that they are worried that the UK might negotiate a free trade agreement with Greenland, for the very same reason's that the EU are encouraging "ever closer union" between them, and I don't just mean the fish. We shall see how it plays out.