OpenWRT stable build 21.02 is now available for the R2S. https://firmware-selector.openwrt.org/?version=21.02.0&target=rockchip%2Farmv8&id=friendlyarm_nanopi-r2s This version includes Luci and ran on my hardware just fine. Here is a video of the a speed test on this version. https://youtu.be...
Not sure if this is what you were looking for but here is a video of various devices being powered by poe splitters.
https://youtu.be/ZFRf8p7H8mo