I heard that some Danes are proud of having the largest country in Europe. Selling Greenland would certainly change that. But as I am not a Dane myself, take it with a grain of salt (and it might not be true either, depending on how you measure other countries e.g. Russia).
The tectonic plate separating North America from Europe goes right through Iceland (the only place the Mid-Atlantic ridge is above water), making Iceland a “country on two continents”.
If a European country can count off-continent lands in its “biggest country” argument, don’t all overseas territories get that consideration? Are the Danes really the last large “empire” in Europe, if only by land area?
If Britain could count Commonwealth countries (they are technically all under the same sovereign), then Canada + Australia would keep GB in the top seat, I’d think.