It was reported some days ago that Athletic Bilbao called on the La Liga organizers to look into Barcelona’s financial situation to see if they are able and fit to make such a transfer because they don’t want to lose their key player. However they can still hold Barcelona down if they ask that his release clause be paid in full at one go instead of in installments, this could be a problem for Barcelona and could help them secure their player.
Moreover, with various rumors circulating, now Athletic Club seems quite excited if Nico goes to Barcelona. And Nico Williams is also warned to be more vigilant and aware of the possibility of his position in Barcelona if signed, because it is constrained by player registration.And the rumor is, Athletic Club actually prefers Nico Williams to Bayern Munich than to Barcelona.
Source: Athletic Bilbao prefer Nico Williams going to Bayern Munich then Barcelona.
I didn't actually know when the Bayern Munich talk came into the picture. But I think Nico will fit well in Barcelona than Spain and this will form a better bond during their national assignment with Spain