A dashboard is a report created with CreateNewDashboard(); the native Blazor viewer tag then renders it in the browser.

Place the viewer.
<StiBlazorViewer Report="@Report" />
Load the dashboard. Create a dashboard report and load its template in OnInitializedAsync:
this.Report = StiReport.CreateNewDashboard();

var dashboardBytes = await Http.GetByteArrayAsync("Dashboards/DashboardChristmas.mrt");
this.Report.Load(dashboardBytes);

How it works. Dashboards reuse the report engine, so the same native StiBlazorViewer tag renders them entirely in the browser.
На скриншоте ниже Вы можете увидеть результат выполнения данного кода:

Showing a Dashboard in the Viewer