With N26 you can change the PIN in-app any time you wish.
From the N26 web site…
"When you set the PIN for your N26 Mastercard or Maestro card, it is stored securely in the Mastercard network as your online PIN. However, in some countries, such as France, Ireland, Greece and Slovakia, merchants predominantly use card terminals that rely on an offline PIN. These machines will verify the PIN code against a secure element on your card’s chip, not against the Mastercard network. That is why your PIN code is not accepted at these terminals.
In order for your card to work at these terminals, you first need to synchronize your online PIN to the secure element on your card’s chip. You can do this easily by withdrawing money at an ATM with your card."
Could Starling integrate this feature? I believe it would be the first UK bank to do so.