Oh that's not from a handheld, that happens to be from Kingdom Hearts X[chi] - that lovely browser game that probably won't see the light of day outside of Japan. It also happens to be a very super secret, one-off missable in-game cutscene.
That aside, the KH3 trailer was awesome, though as you said nothing mindblowing. Though people do seem to be blowing up about the fact that Sora had guns, as if he's going to be running around with them and they weren't just a magic finishing combo.
Also, too bad you don't live nearby. I'd say you could raid my collection if you wanted to play the handhelds/Final Mix versions of anything - but the ReMixes are clearly taking care of that.