That, and just working on improving his own biology in general. Stuff like making his muscles denser, able to contract faster, make the body better structured, remove dependencies like blood, food, and air, improving the material his cells are made of, and many, many more things.
Granted, it would be harder and take more time for him to do than it would for Ella, but I seriously doubt he's actually incapable of doing these things.
By understanding biology and practicing super minute transformations, he could not only change stuff like his organs, but also mix and match stuff to be more efficient and powerful, as well as invent stuff from scratch/via inspiration from these things.
This kind of power is literally the most developable kind of power IMO. MC just isn't really practicing it like that.