I can confirm that with the Official Ubuntu image, things work.
I did the following:
sudo systemctl disable amlogic-adbd.service
# Reboot
sudo apt install -y wget
wget https://github.com/radxa-pkg/radxa-otgutils/releases/download/0.1-2/radxa-otgutils_0.1-2_all.deb
sudo dpkg -i radxa-otgutils_0.1-2_all.deb
# it complains that android-tools-adbd cannot be installed, but that is a harmless error
sudo systemctl enable radxa-usbnet.service
Then, open the file /etc/network/interfaces
sudo emacs /etc/network/interfaces
Add the following content to the file:
auto usb0
iface usb0 inet static
address 192.168.222.2/24
gateway 192.168.222.1
Now, reboot the radxa zero.
The computer that it connects to will see a usbnet interface (tested on Mac and Linux). Have that interface’s ip address to 192.168.222.1, and enable Internet Sharing (mac).
Then you radxa is sshable at 192.168.222.2 from your usb-connected computer, and also uses internet from your computer.