knowing nomura as we do you don't he will make sora cannon in this cameo lol
Of course he will. Lann and Reynn will be in KH3, obviously. They fall through a door in Nine Wood Hills leading them to the Kingdom Hearts universe and find themselves under attack by some vicious Heartless. Their Mirages aren't enough to take them down, but thankfully Sora, Donald and Goofy were passing by.
Lann: "Woah, Reynn check it out! Sora's a Jiant!"
Sora: "I'm not a giant! I'm just me like always, Lann. But you look a lot shorter now...Weren't you a lot bigger?"
Lann: "I'm not short! I'm a Jiant!"
Reynn: "[aside] Oh no, there's two of them..."
And come to find out they'd been summoning Sora from out of the KH universe into Grymoire. Because of how time is different between universes (thank you established rules in WoFF), time would not move in the KH universe so Sora didn't think much about it.
Donald: "You were being summoned to another universe and you didn't tell us!?"
Sora: "I didn't think it was real, so I never thought about it!"