Wouldn't it be cheaper and better for the environment to buy some land off Germany or Sweden? Once the deal is sealed, they could start building the city the very next day.
Back in 2016, the Norwegians had an idea to gift Finland a new highest peak by shifting the border between Finland and Norway just a bit as Finland was due to celebrate its 100th year of independence. However, it never actually went anywhere since it'd be unconstitutional for Norway to start splitting off its country.
It's a stupid prestige project, primarily designed to attract rich investors, who will let their investment object apartments sit empty, creating another dead neighborhood.