Change Pi Pico Serial Pins

Hello,
I am working with a respberry Pi Pico board.

What I want to do is to change the pins of the UART0 channel. According to the picture in https://forum.arduino.cc/t/pi-pico-arduino-ide-pin-mapping-for-gpio-in-ide/903691 there should be plenty of alternative pins for the UARTs.

Specifically, I want to put the UART0 channel to GP16 and GP17.
My understanding is, that the definition of UART0 is already hardcoded into the arduino framework.

Is there a way to change the pins of the UART without creating a completely new variant?