Not sure if it useful here: With the help from Armbian forum I figured out how to enable/disable and configure some GPIO ports (eg I2C) on the current armbian RockPi4 image (beta)
# enable i2c7
cd /tmp
wget http://ftp.debian.org/debian/pool/main/d/device-tree-compiler/device-tree-compiler_1.4.7-3_arm64.deb
chmod +x device-tree-compiler_1.4.7-3_arm64.deb
dpkg -i device-tree-compiler_1.4.7-3_arm64.deb
cp /boot/dtb/rockchip/rk3399-rockpi4b.dtb /boot/dtb/rockchip/rk3399-rockpi4b.dtb.bkp
dtc -@ -I dtb -O dts -o rk3399-rockpi4b.dts /boot/dtb/rockchip/rk3399-rockpi4b.dtb
#edit section i2c@ff160000 in .dts file
status = "okay";
clock-frequency = <400000>;
dtc -@ -I dts -O dtb -o /boot/dtb/rockchip/rk3399-rockpi4b.dtb rk3399-rockpi4b.dts
status can be disabled or okay.
clock-frequency is optional and can be increased for use-cases like the OLED display from default 100kHz to 400kHz.