in ag-grid single column Grouping, there is this property called showOpenedGroup that lets you display the same value as what is being grouped by:
https://www.ag-grid.com/react-data-grid/grouping-single-group-column/#showing-open-groups
But I find it weird that the values (being the same as the group) are indented one level down, see the attached image: indentation
I would expect "United States" (child) to render with the same indentation as "United States" (group parent) because they are the same value. One is not a child of the other, they are the same.
I tried to look for any property or css variable to override this behavior "the right" way, but it seems it is not possible.
Did you try this css class?
--ag-row-group-indent-size