Reportedly Barcelona is considering selling De Jong, Raphinha and several others. Ansu Fati, Eric Garcia and several other players could also be Barcelona's choices to get this budget, but as you said, I also don't know for sure what steps Barcelona will take to meet the hopes of their new manager next season.
I don't expect De Jong to be sold, nor do some defenders like Araujo. The team's current financial needs are very urgent, but it is still possible for Laporta to get sponsor support to allocate some of it for player spending. Hansi Flick knows what he has to do at the start of his first season, especially in pre-season, he has to try to find the best formula and lineup of players to be included in his main line-up next season.
I hope Barcelona does that especially to sell De Jong. How could their club's finances be so messed up just to pay one player every week? If I'm not mistaken De Jong's salary for that week was 730k Euros and it was very unreasonable with his less consistent performance and frequent injuries making him the player with the highest salary at Barcelona.
It is possible that Hansi Flick should give advice to management to sell some of his players and he can target the players he needs in the squad. Because this is his first season managing Barcelona, he will definitely be careful and not want to make a mistake. Full trust in him must be repaid by winning one trophy at least next season.