Governments aside, which nations have majorities of people who would even want a United States of Europe at this point? This seems like something everyone wants as a long term goal but would never go for in the medium term.
Literally none. Even in Germany, polling is against it, and the EU as it stands is much more unpopular in most other member states. The SPD has a deathwish, it seems. If they drag the CDU along this path, AfD and Linke will become the top parties in East Germany, ironically the opposite of what the grand coalition would want.