Getting Ubuntu onto your Pi is straightforward thanks to the Raspberry Pi Imager tool.
Are there (like Docker or Home Assistant) you need to install? ubuntu for raspberry pi 4 8gb
Or use dd / BalenaEtcher.
Ubuntu is more resource-intensive than the standard Raspberry Pi OS. On 2GB or 4GB models, you might see "swapping" or lag when opening multiple browser tabs. On the 8GB model, Ubuntu runs smoothly, allowing you to keep VS Code, Discord, and Chromium open simultaneously. Choosing Your Version: Desktop vs. Server When you head to the download page, you’ll face a choice. Getting Ubuntu onto your Pi is straightforward thanks
From ubuntu.com/download/raspberry-pi :
20.04 LTS – outdated kernel & poor Pi 4 support. Ubuntu runs smoothly