I'd understand to make a PS5 SKU/native patch adding the basic PS5 features like fast loading or adaptative triggers copy pasting some stuff from Forbidden West or the PC port like some accessibility stuff, plus maybe to unlock FPS or resolution.
But I highly doubt they would be making a remake or a remaster as a separate product. Sounds like a fake, specially seeing it's coming from an unknown random website.
Regarding having a canned Monster Hunter-like coop game mode and turning it into a spinoff, it's something I can see. Specially considering Sony has multiple unannounced GaaS games, and the Killzone 2 MP+Rainbow 6 Siege director working on an unannounced game.