Hi Ugo,
Greetings from Syncfusion Support,
Based on your query, we understand that you
want the collection of the dataSource used in our demo. The dataSource is
already available within our sample demos.
Please refer to the attached image.
Image ref:

Demo link: https://blazor.syncfusion.com/demos/gantt-chart/editing?theme=bootstrap5
When you navigate to the Source tab, you will find two sub-tabs: one for
the Razor file source code and another for GanttData, which contains the
dataSource and the model class.
If you have any further questions or need additional assistance, please let me
know!
Regards,
Ajithkumar G