Canada is associate member of the EBU. Thing is you can only be a full member if your territory falls within the EBA, which isn’t even defined by the EBU but the ITU.

There’s precendence for associate members to participate in the ESC, though, to wit, Australia, and if Canada were to become a EU member I bet they’d also be allowed in. I also very much doubt the organisers would deny Greenland entry.