The Partenopei were tracking both strikers as priority signings back in 2020, but when Haaland snubbed them to sign for Borussia Dortmund instead, Napoli went all in on Osimhen.
Giuntoli explained that according to their evaluations at the time, Napoli considered both strikers to be at around the same level.
"The contract with Salzburg was done already, we would have paid his €25m clause," he told Il Corriere Dello Sport when asked about missing out on Haaland.
"He and Osimhen were our priorities and when Haaland opted for Borussia Dortmund, we went for Victor.
"To us, they were on the same level."
Osimhen has quickly become a star striker for Napoli since joining the club. The Nigerian international has scored 38 goals and provided 12 assists in 76 appearances for the Partenopei across all competitions.
Haaland has meanwhile been unstoppable in his first season at Manchester City, where he has scored 23 goals in only 18 appearances.