If you need to use Linux GPIO in Ruby, please see denko-piboard or lgpio instead.
This gem only contains some (probably bad) code, extracted from an old version of denko-piboard. I started building that on top of libgpiod directly, but eventually settled on lgpio which has more features and was simpler to implement.
At some point, I will probably finish the libgpiod implementation, and substitute it where applicable in denko-piboard, in place of lgpio. It performs ~15-20% better, but lgpio + YJIT is already pretty fast, so this isn't a priority.