JS eligibility in any of these scenerios?

[Rachel Guido]

On my paternal side:

My grandfather Giovanni was born in Italy, 09/1900. He immigrated 06/1913. My great-grandfather father filed a D of I 09/1913, a certificate was issued 06/1920. My father was born in 1951.

Did my grandfather receive derivative citizenship because he was under 21? He never filed naturalization papers, but did list he was naturalized when he joined the Navy (not sure of the exact year). I found this on the Familysearch.org Wiki site, which caused confusion: “Derivative citizenship is defined as obtaining one's citizenship from or through another person. When the child's father became naturalized, his children under 16 (or 18, depending on the year) automatically became citizens. No paperwork was created at that time. From 1790 to 1929, to prove his or her citizenship, the child would need his or her father's certificate of naturalization.”

My grandmother Fortunata was born in the U.S. in 1911. Her parents immigrated (separately) in 1907 and married in the U.S. My great-grandfather was naturalized in 1928, my great-grandmother did not naturalize. Again, my dad was born in 1951.

My husband’s maternal side:

His great-grandfather naturalized in 1938. His great-grandmother never naturalized. His grandmother was born in the U.S. in 1921. His mother was born in 1949.

Curious to see if either of us could pursue dual citizenship. Any help is greatly appreciated!