Hi,
You could use the below code to display .stylx file created from Pro. Attached is the sample application.
string file_to_stylx = parent.FullName + "\\Data\\style.stylx";
symbolStyle = await SymbolStyle.OpenAsync(file_to_stylx);
IList<String> stringList = new List<string>();
stringList.Add("shoppingcenter01"); // key file, you can get this key by opening .stylx file in SQLite database
SimpleRenderer simpleRenderer = new SimpleRenderer(await symbolStyle.GetSymbolAsync(stringList));
newFeatureLayer.Renderer = simpleRenderer;
Hope that helps.