This book will mainly be about story/chapter concepts. For example Akira travels to the Jurassic Park universe and/or the kung fu panda universe.
Cinderwing meets the rescue riders.
Someone is reborn as a Godzilla hybrid in the monster-verse
A transformers movies/prime/earthspark story whether It's Akira visiting, someone being reborn or where the mc is a Oc
A dinotrux story
Flashbacks of Akira's time in the First Realm and maybe some suggestions but that would depend on whether I've seen or have access to said movie/tv series