I agree, this one is kinda weak. Too much spent on info-dumping, not enough spent for getting into the heart of the matter.
This one-shot should've just started around when the BlackAgumon digivolved into BlackGreymon and Hinata took care of the DigiEgg. The subplot of Hinata not having the phone could've just been skipped or condensed into two, three lines so that the hacking part of the story started from the school hacking instead.