Odegaard is way way overrated. Even at his worst, FdJ is not losing any ground to the best version up to date of Odegaard.
The potential of FjD is a Roll Royce of a deep play maker, that people seem to forget. He's press resistant to the extend that you feel like he's the Messi of this part of the pitch. Throwing a few players to press him even if he's facing his own goal is no use.
The issue at Barcelona is not he's struggling with the level, but the style. Barcelona system want to play more short passes, and other players in the build want more touch on the ball, where as FdJ is touch greedy. This is worse when Messi was still around, as Messi wants to get involved and having many touches in possession too.
At Ajax, FjD pretty much ran the show when they build up from deep. They kinda take the make the pitch large principle to the extreme with him; where his teammates kinda stay away from him. This allowed them to overload in other parts of the pitch having opposition hand full. FdJ alone often broke through the first press, without involving his own teammates in complicated triangle, tiki taka. FdJ is also athletic and capable defensively.
I never this level of potential in Odegaard (Require plenty more water carrier, and way less outstanding in individual brilliance). Well worth to doubling the fee if FdJ is attainable.