If I buy the game on PC, can I keep all the stuff I have on ps4? Because I have A lot of hour on that game on ps4 but more friends on PC, so I don’t want to restart all for that.
Unfortunately, you cannot.
even with the battlebox log in?
Yep. Sorry, bud…
Theoretically, if Battleborn works the same as Borderlands 2 did, you could. Unfortunately I think it breaks Sony’s Terms of Service and Steam probably won’t like it either. So I’m afraid you’re out of luck.
Yeah, they’re seperate. Otherwise i wouldnt have the weird diverse masteries i have on both platforms 
(noticed today on ps4 i had no lore done as pendles- hes been done on pc for me for months, as on example)