It would be awesome if you would have a feature to change the card PIN inside your app after you received and activated it.
Yes many ATM’s have the possibility to change them, just not in Germany at least. Here you can change your PIN rarely if it’s no card from the issuer bank of the ATM.
I’m unsure about the mastercard regulations and rules, as I have never seen this function in any other app (I have quite a few of those haha ). But I think it would be an awesome feature if it’s allowed to implement something like this.