MacOS can display a concise, linear graph showing what percentage of disk is used and the relative amount of different kinds of data.
What is the name for this kind of graph? I wouldn't call it a pie chart or a bar chart.
I've seen this referred to as a single stacked bar chart (without the axis indicators).
It's also been called a segmented bar chart.
Since there is not any single running process, its goal is understanding the distribution of storage, and displaying proportion. There's not any progress to speak of, just distribution.
Indeed, it's a stacked bar chart. https://datavizproject.com/data-type/stacked-bar-chart/
The whole Dataviz Project site is a great resource on various data visualisation tools for future reference and consideration.
I think the name is: Progress Bar Chart