Actually PSG didn't want him anymore because for Luis Enrique he wasn't good enough with his feet. For me a goalkeeper should mainly be able to save goals rather than being good with feet, otherwise just play with a midfielder in the goal, but I'm no coach... Chevalier better play the season of his life because last year PSG won the Champions League thanks to Donnarumma's saves.
Wanting a goalkeeper who is good with his feet doesn't mean the keeper shouldn't be able to make saves; it means he has to do both.
The way the team plays, they play from the back and having a keeper at the back who isn't good with the ball on his feet is a disadvantage. The keeper needs to be comfortable on the ball even when he is pressed, because if he meets a team that presses very well, instead of gently passing the ball to his teammates, he will shoot it out, and the ball might get to an opponent who will have a chance to score. Even if it gets to a teammate, there will be no rhythm in the way they play if the ball is constantly launched in the air by the keeper.
The only problem is, he is now heading to a team that requires the keeper to play from the back, so if he was not good for that system at PSG, how will he be good at it in City? Which leads me to conclude that there is more than we know. I don't think the reason he's leaving is because he is not good with the ball on his feet; there is more.
My theory is that they saw a younger keeper who was potentially better, and they needed to take him before another club does, and since he could not be second choice, they had to sell Donnarumma because there is no way a player like him earning about 12 million a year will be a second choice.
Younger goalkeeper? Donnarumma was born in 1999 and when he was 16 years old was playing for AC Milan in Serie A; Chevalier was born in 2001, he is 2 (two) years younger than Donnarumma and made his professional debut in 2021 in Ligue 2; he only played in Ligue 1 in 2022 when he was "already" 21 years old. That means Donnarumma despite being only 2 years older than him, already played 10 years of first team football in a major league while Chevalier only 3. There is no comparison between the two, Donnarumma is clearly way better.