I believe Niue is the smallest Self Governing country.
Self-Autonmy
Commonwealth
Canada joined the Commonwealth after it became self-governing.
Puerto Rico is an unincorporated, self-governing territory of the United States and styles itself ( in English) as the Commonwealth of Puerto Rico. Its name in Spanish, Estado Libre Asociado de Puerto Rico, is more literally translated to English as "Free Associated State of Puerto Rico."
Yes, Pennsylvania was a self-governed colony.
Denmark has two self-governing possessions.
Self-Autonmy
Yes.
Denmark
Domninion
Australia is both the smallest continent and a self-contained country.
Commonwealth
1867
Japan is an independent, self-governing nation.
Greenland is a part of Denmark.
Russia is a self-governing sovereign nation.
Commonwealth