Unfortunately, the KendoReact PivotGrid sorting is currently supported only for string values. This means that even if you set the field type to "date", the sorting will still be applied as if the field were a string. You can see that in this example: https://dojo.telerik.com/oZoTuMIC/55
Please extend your sorting mechanism so that the sorting covers types such as dates and numbers too. Please also consider the user's language when implementing this sorting. We receive date fields in the format yyyy-mm-dd and they should then be displayed in the user language in the UI. For example in German dd.mm.yyyy (i.e. 21.11.2021) or in English 11/21/2021. And please offer this feature for local data binding too.