The Deep Hollows – Joshua Farmer

This book is disguised as Isekai - a human is reincarnated on another world, and starts gaining power. As Isekai, it is quirky: The human’s soul has been hijacked, and manages to get away and incarnate as a blob. (Initial improvements come slowly.)

There is a bigger picture. The protagonist’s transformation is a result of plotting and interaction between major powers - ‘major’ as in “entities with competing opinions about whether and how the universe should be destroyed”.

The book’s end opens into a much larger story - in which the protagonist may become entitled to a say in whether and how the universe should be destroyed.