They won't sign Fofana. It's clear they want a player that can step up if Lamine/Raphinha are injured or need rest, or just for rotations in general. You won't see them signing a project or developmental player unless Fofana is as talented and can make the step Doue and Barcola did immediately after joining PSG.
I haven't watched enough of him to say whether he is at that level or not.
As for the other options of Diaz, Nico, Leao, Rashford, Lookman then all of them have their own issues where you will not find a consensus among the fanbase.
As serghei and others have said, the price will be the key factor here. You cannot sign a winger who will be 29 years old next season for more than 40-50m euros in total max, and even for this price there are some issues as you don't know if the decline will hit soon or in a few years. There's no guarantee you will be able to sell him to Saudi either because very few players want to leave Barcelona after they have joined us.
I'll also say that when PSG signed Kvaratskhelia for 70m + 10m in add-ons, then none of the wingers we are linked to should even match the fixed price of 70m. None of these guys are better than him, and the club have to be smart about who they sign.
It's not just about the price, but the opportunity cost as well. If you sign Diaz or Leao for 60-70m and they flop then not only have you failed at making the team better, but you've also chosen possibly better options ahead of them and maybe even lost out on better players that become available in 2026/2027 with how our financial situation/salary cap situation is.