Create a pie chart from amount/category pairs

Question

From a table like

Amount | Category
  2        A
  1        B
  5        A

how to create a pie chart with one sector per category found in the second colum and the summed up values for each category? In this example two pies: A=7, B=1

There is an answer to a similar question for Excel that uses a pivot table: Create a pie chart from distinct values in one column by grouping data in Excel.

Is there an easier way in libreoffice?

How to create a pivot table for this scenario? When selecting both columns, the menu Data - Pivot Table - Create is not available (Documentation).