As the resident Nico Williams gospel spreader on the forum, I can take a shot @Don Pacifico.
I would start by saying I don't believe the stats tell the complete story with Nico and you do have to watch him a decent amount to get a better picture of his value since no one is going to be too impressed by 5 goals and 11 assists in La Liga last year in light of the excitement that surrounds him. First of all, he's lightning quick and would easily be the fastest player on our team, supplanting Martinelli. He's also very quick with the ball and has an explosive first step to get by defenders, both in transition where he is Bilbao's best method of ball progression and in settled states of play where he likes to face up defenders and then burst past them with a quick (and usually quite simple) move to either side. He's also got the self belief and confidence to back up his physical traits and always looks like he feels he can get by any defender at will.
Aside from his pace, my favorite aspect of his game is that he is quite two footed and has great ball striking on either foot. His primary instinct thus far in his career (he's only 22 and broke through with Bilbao in 21/22) has been to beat his defenders and then look to cross the ball but he's started to look for goal more recently and has a nice catalog of great finishes from the last two seasons already. Add that to his standout performances at the Euros opposite Lamal and it feels like this is his true breakout season where he can get into double digit goals and become a household name. Comparing him to some of the other big name wingers out there like Leao, he clearly doesn't have the production that Leao has had (although he's 3 years younger) but I think he's already more well rounded as he came up playing fullback a bit and definitely can put in a shift pressing, an area where Leao is lacking. He's certainly not the finished product and you'd be paying for a bit of future projection in addition to his current talent but given his growth over the last few seasons and his impressive physical talents, he's one I'd be willing to bank on stepping up to the world class level in the next season or two. The only (realistic) wingers I'd want more at this point are Kvaratskhelia and Rodrygo.