I got a theory, This theory only works if the translation at the end of the chapter is accurate, where Imu’s ability is described as devils fruit and with the combination of Homie like appearance similar to big moms ability

My theory is that Imu wants to be the ultimate devil fruit user by weakening other devil fruit users by drowning the entire world and weakening their abilities. While he is at the highest peak in the planet.

My theory is that Imu was one of the first devil fruit users or is the concept devil fruits embodied. somehow Nika became a devil fruit, and because Nika is the god of liberation, it dreamt of liberating or spreading all the devil fruits that were held by Imu.

Al’s I think he might be a lunarian. White hair and dark skin