Kuroki_Shishiro
well it's basically impossible for this story to long due to the mere fact that MC is OP with his adaptation so idk author just do what u must but when u say about him going to another universe, will he go to Honkai impact 3rd or HSR because there is no way he can go beyond the quanta sea or the imaginary tree to reach the other anime verses unless he reaches the pinnacle of Hoyoverse
second option if you have the motivation and patience to do it. Doing a shorter approach and finishing it earlier is better than to flesh it out and lose motivation in the middle. Im fine w either but a longer story w more world building and character development would be fire. Think of all the possibilities, defeating archons, going against celestia heck you could end it on a tbc note and make a sequel in another world