It's far less costly and immensely more profitable for Sony to just port PS4 games to Steam and let them run on Steam Deck.
A portable PS4 is not possible using its existing hardware and any new hardware design would require Sony to assign a team of software engineers to port software to it, that is a far higher investment then just porting older PS4 games to steam.
A portable PS4 is not possible using its existing hardware and any new hardware design would require Sony to assign a team of software engineers to port software to it, that is a far higher investment then just porting older PS4 games to steam.