Following this guide from QEngineering.eu.

  1. Download ubuntu 18.04 LTS (bionic beaver) server edition here (choose the 64-bit ARM version, which is for Raspberry Pi)
  2. Install Raspberry Pi Imager here
  3. ...couldn't get Ubuntu to boot headless using WiFi, so I'm scratching that for now and trying RaspberryPi OS 64 for Raspberry Pi Zero 2.

(ABORT!)

 

On a sidenote, I found a cool Github repo that creates a WiFi AP while still connected to an AP (in client mode).

Also, here's how to connect to WiFi in Ubuntu using CLI.

Also see https://gist.github.com/tcr/4192613#file-code-sh