Hi @aeroh,
Very interesting case, thanks for sharing! With the steps below you should be able to meet that requirement. 😊
(1) Change the Items property of the PieChart control
With(
{
wRecords:
ForAll(
Filter(Choices(Inventarliste.Status);Value="In Verwendung" Or Value="Verfügbar") As A;
{
Number:CountIf(
ForAll(
Filter(Inventarliste;AssetType.Value = Dropdown1.Selected.Value);ThisRecord.Status.Value
) As B;
B.Value = A.Value
);
Value: A.Value
}
)
};
//Add column for displaying percentage
AddColumns(
wRecords;
"Percentage";
$"{Number} ({Round(Number / Sum(wRecords;Number) *100;2)}%)"
)
)
(2) Select the PieChart control, navigate to the right property panel and select 'advanced'. Set the Labels and Series properties to the following:

(3) Select the Legend control, once again navigate to the advanced section in the right property panel. Here you will have to change the Items property from PieChart1.SeriesLabels to the full code of your PieChart Items property (copy - paste the code of step 1). The Value dropdown will have to be set to the 'Value' column.
(4) Optional yet recommended: Save the PieChart Items code to a collection e.g. in the OnVisible of the screen. This way you can avoid copy-pasting the complex code (and Power Apps executing the code twice). Afterwards, set both the PieChart and Legend items properties to that collection.
If this solves your question, would you be so kind as to accept it as a solution & give it a thumbs up.
Thanks!