and just in case, but I guess Martin already solved your problem.
Within armbian you find following User-Supported options for GPIO and more:
ArmbianIO (sysFS) or
pyGPIO accesses 'pins' directly through /dev/mem
ArmbianIO API - in C https://forum.armbian.com/topic/5655-armbianio-api-proposal/
User Space IO - is Python 3 and Java 8 bindings for user space GPIO, SPI, I2C, PWM and Serial interfaces https://forum.armbian.com/topic/6523-user-space-io-is-python-3-and-java-8-bindings-for-user-space-gpio-spi-i2c-pwm-and-serial-interfaces/
pyGPIO - A 'more general' python GPIO library based on pyA20 https://forum.armbian.com/topic/5662-pygpio-a-more-general-python-gpio-library/