I personally believe Don Carlo (although I believe he was the Greatest Boss, discussion for another time) would be a boring film, as a stand alone focus. I just don't think of him as an exciting character.
Now Vito Genovese on the other hand would definitely be interesting. The time under Luciano, working for Mussolini in WW2, the power struggle with Costello, then being set-up for drugs by the other bosses. That's a flick.

Just throwing this out there I think Martin Scorsese blew the "last great mafia film" thing on The Irishman. It was 20yrs too late, too long and too untrue. Pesci as Russell Bufalino was the the only good thing about it but that cast could've been used in a say Commission movie.
Joe Pesci as Tommy Lucchese (similar to the Bufalino character)
Al Pacino as Don Carlo Gambino
Harvey Keitel as Vito Genovese
Robert De Niro as Joe Bonanno
Ray Romano (who was actually good in Irishman) as Joe Profaci?
Sounds good on paper lol maybe it would be better withe some younger actors......

"Joe Bananas went after Carlo Gambino, the war went on for seven years..... When guys go to the mattresses, they're not out earning" -Tony Soprano