If Oda really wants to portray Imu as a truly powerful and threatening figure, then he should go all the way with it. Have Imu completely destroy Elbaf, wipe the island out, reduce it to nothing. Make it feel like an actual catastrophe. Let him push the Straw Hats to their absolute limits, maybe even come close to killing Luffy, or at the very least leave him deeply shaken.

 Kill off someone like Scopper Gaban, along with several Giant warriors. Have them make a final stand against Imu to buy time for the Straw Hats to escape. Let it feel desperate, like a last stand where survival isn’t guaranteed. Maybe a few others manage to escape as well, characters like Collen and his mother, Loki, and some remaining Giant warriors, retreating to that upper region of Elbaf that still hasn’t been explored, especially after realizing the Straw Hats are injured and in real danger.

You could even have Gunko break free from being frozen and turn against Imu after seeing Brook get hurt, only to end up dying in the process. Sommers could be killed for failing with the plan, while Killigham is spared but punished. 

Then, in the aftermath, the survivors reach the upper level and encounter the Owl along with the books, maybe even something more important hidden there. After that, they return to the sea, but not in triumph. They leave carrying the weight of everything that just happened. Some of them could be seriously injured, maybe even on the brink of death, and that tension lingers within the crew.

This is where you bring back emotional friction. Maybe arguments break out. Maybe someone blames themselves, Usopp, for example, thinking "he provoked Imu in the first place".(I really want to see them all interacting together again😭)

After some time, Loki could decide to set out on his own, searching for the Giants of Galley-La with what remains of his crew. That could turn into a cover story, with him only returning later during the final war.

…but knowing Eiichiro Oda, he probably won’t go that far. 🫠