Hi Andrey,
Thank you for your feedback.
Please keep in mind that RadCalendar in Xamarin is not RadScheduler in .NET MAUI. In .NET MAUI The Calendar is a separate control, and the Scheduler is another control. The .NET MAUI Calendar exposes SelectedDate: https://www.telerik.com/maui-ui/documentation/controls/calendar/selection#changing-the-selected-date
Regards, Didi Progress Telerik