Refer: https://itsfoss.com/install-themes-ubuntu/
$ sudo add-apt-repository ppa:system76/pop
$ sudo apt-get update
$ sudo apt-get install pop-theme
$ sudo apt install gnome-shell-extensions
Clear default launcher setting in Droid
I'm using a custom launcher/theme, and it might be necessary to restore it, or use it in parallel. These steps can be used to reset the default behavior.
Clear default in Home Settings > Applications > Manage Applications