Hi Pawel,
Greetings from Syncfusion.
Query1: Is there any way to define selected item template?
We can achieve your requirement by defining the ItemTemplate API of SfComboBox control and binded to the ViewModel properties. We have created a simple sample as per your requirement which is available in the below link.
Query2: Is there any way to set selected item from code or by binding in xaml?
Yes, we can bind the selecteditem from either code behind or in Xaml code itself and in the above sample we have binded a default value to the ComboBox. Please have a look and if your requirement differs provide us some additional information on your requirement.
Please let us know if you have any concern.
Regards,
Paul Anderson