Tbh, it would be better if we got someone who fits our style more. People say only about Pep, but even the different Barca team under Rijkhaard who were more direct and physical still played 4-3-3. Liverpool currently play 4-3-3, I think even Leipzig and PSG also 4-3-3. To play 4-2-3-1 you need a strong pivot "9" who can play more isolated, like Haaland or Lewandowski.
4-2-3-1 would've been good back in Valverde's days. When you rebuild, you rebuilding having in mind the best system for the club going forward.
We are shit, so we have nothing to lose.
What we should do is move to a 4-3-3 right away with De Jong, Pedri and Puig midfield 3. Busi is done, Pjanic is never a player for a rebuild since he's slightly better than Busi but in the same boat really. So, just work with this front 3 which is the only one we have now looking at the future. Try to build some chemistry between them. They are all young and energetic and good with the ball, and 2 of 3 are fast as well.
When everyone is fit, I'd expect ideally De Jong - Puig - Pedri, Fati - Messi/Griezmann/Braithwaite - Dembele.