Folks, I just solved the Greenland problem.
1. Canada ditches Charles as head of state (we aren't getting any ROI on that relationship)
2. We name the king of Denmark as our HoS instead. IDenmark is already the only other country with which we share a land border!
3. Now that we are in a personal union under a sovereign of a EU country, Canada can join the EU
4. Canada can now freely deploy forces in Greenland
This also has the side benefit of resolving that maritime border dispute we have with Greenland. It's all upside, other than having to relearn temperature scales for ovens and swimming pools.