Thanks to the Microsoft fabric community, I found the proper way to do:

To make "Selling Object" a single category (instead of multiple columns), we need to unpivot the data.

First open your Power Query: Select the table containing selling obj 1, selling obj 2, and selling obj 3.

Then Highlight the columns selling obj 1, selling obj 2, and selling obj 3.

• Click Transform → Unpivot Columns. Power BI will now create two new columns: "Attribute" (which stores "selling obj 1", "selling obj 2", etc.). "Value" (which stores the corresponding values).

Next rename Columns

• Rename "Attribute" → "Selling Object".
• Rename "Value" → "Sales Amount".

Then just create your pie chart!

• Drag "Selling Object" into Legend.
• Drag "Sales Amount" into Values.
• Now, the pie chart will group sales by Selling Object.

https://community.fabric.microsoft.com/t5/Desktop/breakdown-measure-on-pie-chart-for-Power-BI-data-managing-issue/td-p/4422136#M1375217