Sounds almost like the concept of Alpha mutation - unlocks human potential and forcefully genetically alters the human genome to correct to a more optimal state without the body swap.

In universe, your idea could half work in the way Exodii function if it is expanded to allow you to become an exodii candidate,they are essentially brains( and whatever necessary organs) in a metal suit. I not sure on their organic to inorganic ratio but they have a lot of bionic knickkacks that imply that their biology works in tandem with their machinery and could open up potential that you use machinery to compensate for your weaknesses… although current bionics do give you some flat passive bonuses which you can try min/max with mutations.

And there are primers and specific mutagens in the labs if your character is too low intelligence to make it. Although getting the exact mutagens can be tricky if you can’t make them specifically.

I don’t know if it will ever have isometric fallout level of intelligence detail, but I personally handwave it away that if you have your facilties then you are “intelligent” enough to learn albeit at various degrees of success thanks to the chemicals in the water.

Not the greatest answer, but it helps me with my suspension of disbelief