There is no feasible method to create a portable device for an economically viable price that would be able to play PS4 games.
Sony is absolutely killing it with the PS4. They have completely dominated the generation. They have zero interest or reason in developing another portable device. It's not happening. Their R&D is going full-blast into PS5 planning, development, and tweaking. They have abandoned the portable market and the latest fiscal report shows that to have been an extremely financially prudent choice.