This is a small disk usage meter widget for Übersicht. Design was inspired by Memory Bar, by cobyism.
Check df -l and find the disk you want to show.
Open index.coffee script, and set the disk_index variable to the line index of the disk (beginning from 1 for the first disk).
On Catalina, the index seems to be 2 for the main disk (which is default). If you are using the older OS, it should be 1.
Clone or download this repo and unzip the archive in Ubersicht widgets folder.