OK, I will try a shorter post this time. I have got Armbian 20.09 (buster_current_5.8.10) up and running on the Ugoos Am6 plus (the newer version with s922xj SoC) using the supplied dtb for Am6. Everything seems to work fine (ethernet, usb, graphics, sound, video playback (see below) and Bluetooth) except wifi. The clock speed cannot be set (in arbian-config) above 1992MHz however, and I have a similar problem with the picture (thin colored vertical lines at the borders of the display) as tonny above.
dmesg_UgoosAm6plus_Android_edit.txt.gz
dmesg_UgoosAm6plus_Armbian_20.09_5.8.10-arm