Raspberry Pi 4 with Ubuntu 20.04: can't install ROS Melodic

edit

I installed Ubuntu Desktop 20.04 in Raspberry Pi 4, but I found that I could not install the full ROS melodic in it. From what I found in forum, Ubuntu 20.04 not support ROS yet.

Here are some other options that I tried but it does not work out 1. Ubuntu 18.04 works well for ROS Melodic but I can no longer get the desktop version for my Raspberry Pi 2. Ubuntu server 18.04 installed for Raspberry Pi, but I can't download the desktop interface for it, keep failing 3. Using Raspbian OS, can't download the full version of ROS Melodic