Including core functions inside library

Hello everyone,
I'm currently trying to add support for RPI Pico to ArduinoUniqueID library for a project I'm working on.
After going through the Pico SDK documentation (by the way I'm using the awesome unofficial porting) I understood that Pico somehow implements ID feature and this can be easily accomplished via the pico_get_unique_board_id built-in function. Now onto the real question:

I managed to get the device ID by writing a sketch that includes the specified core library (#include <pico/unique_id.h>), but doing the same inside the UniqueID library ends up returning always zeros. After doing some debug I discovered that even if the .h file was included just fine, his related implementation in the .c file was not linked, exposing the core prototypes but not their respective implementations.

I've already made sure that the library is wrapped to be included in a cpp file, tried to edit the makefiles and moved files around; bringing the core library inside the library folder and including it with a relative path managed to partially solve the issue, but it's a rather undesirable solution. Any idea why this doesn't work? I'll paste the code I've written for some context.
Thank you for your time.

#elif defined(ARDUINO_ARCH_RP2040)
	pico_unique_board_id_t pico;
	for (int i = 0; i <8; i++) {
		id[i] =[i];