It does fit that Sora's an amalgamation. Since age 4 he's had Ventus in his heart and by the end of KH2 Roxas and Xion are in there. Roxas has a notable impact on Sora in KH2, emotionally (such as through Anti-Form) and to some limited degree physically (his hair is a lighter shade of brown than in KH1). Thematically he's connected people across worlds and time, explicitly stated at the end of re:coded when he's the key to free the Wayfinder and Twilight trios from their suffering. He's used "my friends are my power" multiple times, at one point even summoning images of all the keyblade wielders and allies shown by that point in the franchise (during the end of his storyline in Dream Drop Distance just before the Xemnas boss fight). It was a big part of his speech when the Kingdom Key decides its true allegiance to him in the first game. It is a shame that the "wand chooses the wizard" aspect for keyblades wasn't explored more deeply, instead going for "you get a keyblade, you get a keyblade, everyone gets a keyblade!"
Yep, Data Sora. Maleficent is able to destroy his data rendered keyblade because it's data. However during his first trip to the data rendering of Hollow Bastion and travelling through with Goofy and Donald, he's able to manifest one on the strength of himself as an individual, not a digital doppelganger of Sora.
As Mickey says: