Greeting from Syncfusion.
We have analyzed your query, based on provided information and we suspect that you have referred the native nugets in Xamarin.Forms project, so only the reported error occurs. For Xamarin.Forms you have to use Syncfusion.Xamarin.SfPicker only in all the Xamarin.Forms projects.
For more information please refer the following link.
Please let us know, if you face any problem.
Muneesh Kumar G.