Forest (ps4) - Coop playable on PC or alone?

I want to buy The forest for the PS4 and play it with someone with a PC - is that possible?

And then I wanted to know what it's like to play the game alone? Does the number of opponents decrease when you play alone, is that feasible on your own?

No, it is not possible.

Of course you can do it alone, that's logical.

No there's no crossplay in this game. Of course you can also play it alone, only it is less fun alone if you have already played the game in coop