If you run the following, you get a list of the available Ubuntu 20.04 container images.
lxc image list ubuntu:20.04
To celebrate, create such a container.
$ lxc launch ubuntu:20.04 myfocal
Creating myfocal
Starting myfocal
$ lxc ubuntu myfocal
ubuntu@myfocal:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04 LTS
Release: 20.04
Codename: focal
ubuntu@myfocal:~$
There are also minimal Ubuntu 20.04 container images. To enable the minimal Ubuntu container images, run the following:
lxc remote add --protocol simplestreams ubuntu-minimal https://cloud-images.ubuntu.com/minimal/releases/
To view the available minimal images:
$ lxc image list ubuntu-minimal: # all container images, from 16.04 to 20.04.
$ lxc image list ubuntu-minimal:20.04 # view just the Ubuntu 20.04 container images.
$ lxc image list ubuntu-minimal:focal # ditto.
The minimal Ubuntu 20.04 container image is at 113MB compressed.
+------------+--------------+--------+-----------------------------------------------------+--------------+-----------+----------+-------------------------------+
| ALIAS | FINGERPRINT | PUBLIC | DESCRIPTION | ARCHITECTURE | TYPE | SIZE | UPLOAD DATE |
+------------+--------------+--------+-----------------------------------------------------+--------------+-----------+----------+-------------------------------+
| f (7 more) | 7097598acce0 | yes | ubuntu 20.04 LTS amd64 (minimal release) (20200423) | x86_64 | CONTAINER | 113.34MB | Apr 23, 2020 at 12:00am (UTC) |
+------------+--------------+--------+-----------------------------------------------------+--------------+-----------+----------+-------------------------------+