To explain a bit more;
The game uses Sony's PSARC (PlayStation ARChive) format for game data and saves. Because the PSARC format is proprietary, you need to use Sony's own code in order to read and write to them, and hence why they have likely included libSceFios2.dll, which is the Sony Input/Output system (version 2). If they didn't include this file, they would have to rewrite their I/O code from scratch and rebuild the entire format for storing the game's data.
And even if that wasn't the case, the PS4 and the PC are both running on the x86 architecture, so the entire game is not being emulated since the code is compatible between both platforms. The only place that there might be some emulation is in the rendering system, depending on what API the PS4 requires for rendering.