Yes, you can plug in m/kb and get matched with other pc players.

Sony doesnt allow cross progression.

 PS4 does not allow cross progression. You're technically correct that he *can* link his PS4 account but it will do nothing.

i know that as long as he knows his hirez account info he can link it to the ps4 but i’m unsure about the mouse and keyboard.

My friend recently lost his pc and because of that he has to play on ps4, I was wondering:

1. Is it possible to use mouse and keyboard with ps4?

2. Is it possible to use the same account he had on pc so he doesn't have to rebuy every god, remaster every god, etc.?

2 questions about switching from pc to ps4