Currently, the diagram can be exported in the following formats: JSON, PNG, JPEG, SVG, and PDF. We don’t have a support to export the diagram as XML file format. We are checking any sample around solution to achieve your requirement and will provide additional information on March 2, 2023. Please refer the UG inks.
Serialization: https://blazor.syncfusion.com/documentation/diagram/serialization#save-the-diagram-as-string
Export: https://blazor.syncfusion.com/documentation/diagram/export