PSG evidently disagrees. I can't tell which is better just yet, but I have watched Donnarumma a lot to know how he is not the untouchable goalkeeper people think he is. He is prone to mistakes and unreliable at times. The good thing about him is that when he decides to step up, he can be very good, but he's not consistent with it.
Chevalier is also a very good keeper. I guess you haven't watched him much, that's why you rate him so less.
Two players can be agemates but peak at different times. One playing 10 years before the other doesn't necessarily mean he is better. There are players who are 27, yet a 20-year-old player may be better than them. According to PSG at this point in their career, Chevalier is better than Donnarumma.
This statement here is born out of sentiment, cavalier is no where near the level of donnarumma talkless of being better than him presently, if not for the clashes that donnarumma has with Luis Enrique, do you think they would even have that thought of selling him off? No.
And I believe that psg wouldn't have even entertain any interest in him. It's true that chevalier is a good promising goalkeeper but right now, he is not in the same league as donnarumma, so let that sink, let's not be talking about this with sentiment, if donnarumma and chevalier is kept aside and you are given the option to choose any of them, I believe that you will always go for donnarumma because in as much as he is experience, he is still a better goalkeeper than chevalier presently.