In that case, if PSG sells him to another club at the moment, which player will they bring to the club instead? PSG must try to bring a goalkeeper of better quality than Donnarumma to their club instead of Donnarumma. If PSG has any weakness in the goalkeeper position, then no matter how good they perform on the field, they may have to give up and lose. So, PSG should definitely think carefully about this matter and then decide to sell this goalkeeper to another club.
Luis Enrique has made Chevalier their first-choice goalkeeper this season, meaning Donnarumma's career is nearing the end of his PSG career, leaving him with no other option but to find a new club. Chevalier also performed well in his first match against Angers, although there's no comparison because he was facing a weaker team. However, if you look closely Chevalier is a goalkeeper who truly possesses the best abilities, in line with Luis Enrique wishes.
Donnarumma might be PSG backup option if Chevalier experiences an unexpected injury or the goalkeeper, as PSG already has a new goalkeeper this season. However, we haven't seen his full potential at PSG, so I can't yet judge whether Chevalier is better than Donnarumma. Let's see how he performs before PSG actually uses him as their first-choice goalkeeper.
Against Angers, they didn't do much, so PSG need to play a tougher team first to see how strong he is in guarding PSG defense.