How to show the day of the week on the desktop date with Ubuntu 20.04 LTS
To show the weekday in addition to the date and time in Ubuntu 20.04, use the command line tool called "gsettings".
It's a good idea to view your current settings first. So open the terminal and run this command:
gsettings list-recursively org.gnome.desktop.interface
It will return various Gnome interface settings, and the one you are interested in is "clock-show-weekday" (with the value "false").
Set the "clock-show-weekday" to "true" by running this command:
gsettings set org.gnome.desktop.interface clock-show-weekday true
Once you hit Enter, you will will see the weekday displayed with the weekdays shown.