... there are some things that are simply not possible in this universe no matter how many tweaks and improvements you try to make. Self-aware sentient AI is one, small portal Mr. Fusion type reactor that gives useful net surplus energy is probably another.
We do already have a "proof of concept" in that in the universe we have self-aware sentient entities consuming only 100 W and massing (very roughly) ~100 kg (i.e. us).
On the other hand, we know of no natural fusion reactors producing significant energy that mass less than about 1/10 of a solar mass.