Ghost of Tsushima Director’s Cut is the first PlayStation title on PC that uses a new PlayStation overlay, which includes your Friends list, Trophies, Settings, and your Profile. This feature is available on Windows PCs and will be accessible from the in-game menu or, for keyboard players, by pressing the “SHIFT +F1” shortcut on your keyboard.
It sounds like you can access your actual PS network friends and earn PS trophies. I hope that is in addition to achievements on Steam itself and not a replacement. I would imagine many people getting the PC version don’t have a PlayStation in the first place.