The first step is to capture the "C" symbol used for compiling. If you turn on verbose compiler output in the preferences, when you compile one of the very long lines will list "most" defines used. The one to look for is usually starts with ARDUINO_ARCH. With ARM chips, there also various custom ones but with STM usually its ARDUINO_ARCH_STM32*. It's a real wild west with ARM and there are no real consistent standards so it will take a little digging.

Then find the NeoArmMethod.h in my library, and look for a compatible #if defined() to it. A bunch of ARDUINO_ARCH_STM32 are present and maybe just adding the STM32G0 specific to the ifdef will make it work.