The documentation suggests that the serial port is only utilised during boot and f/w upgrade.
I have tried "sudo i2cset -y 1 0x6b 0x02 0x00" to disable the serial port on the Pico, without any joy.
The GPS is connected to pins 8 & 10 on the 40 way header. The documentation says:-
The UPS PIco HV3.0 is equipped with 2 serial ports. One of them is connected directly
to the Raspberry Pi ® Serial Port, and the second one is available for user applications.
Both Serial Ports are full programmable, and the data rate can be set by user, as also
can be enabled or disabled.
I am supposed to be using a port from the Pico ?