Ligue 1 now is becoming a good league in terms of quality players that Paris have and everyone want to watch the game when Paris is playing,it doesn't matter against who.
You are discussing about a league, not a team so only PSG is not enough to help Lique 1 is good league. Ligue 1 has lower quality on average than Bundesliga. I know PSG dominates Ligue 1 and Bayern dominates Bundesliga but there are more competitive teams in Bundesliga than in Ligue 1.
I don't know why he picked PSG when he can't even take the shirt from Navas, maybe a loan move would be better for his development but transfer window is almost closing down. We will see if he can takeover but so far Pochettino is pleased with Navas.
Donnarumma will beat Navas and take the first goalkeeper position from Navas. That time will come because now Navas is the main goalkeeper because he has more experience than Donnarumma. I don't think in comparison about talent and goal-saving skills, Donnarumma is worse than Navas.
On the other hand Messi already did his debut, not a fancy one but he showed who's the boss. Every player try to pass him in PSG, unfortunately he couldn't find a good position in his limited time. I expect a good performance from him after international break. This break is good for his adaptation to his new team, you can see from his face he doesn't believe he is under shirt of another team other than Barcelona. Give him some time and he will show why he is the number one of all time.
Mbappe still played for PSG in that match so will he finally stay in PSG? Will PSG accept the risk that they will lose Mbappe in a free transfer next summer? Or will Mbappe change his mind and renew his contract there?