dual citizenship and naturalization

in europe

https://www.thelocal.it/20210325/compare-which-european-countries-have-the-toughest-rules-for-gaining-citizenship/

Surprisingly, these countries do not allow dual: - Spain - Germany - The Netherlands - Austria

These ones take a long residence period - Croatia 8 - Denmark - Norway

France seems one of the most friendly: - 5 years permanent residency or 2 if you do postgraduate study there