Hi Lars,
Having a filter bar in a GridDataBoundGrid is possible. These are the codes need to be added.
GridFilterBar filter = new GridFilterBar();
filter.WireGrid(this.gridDataBoundGrid1);
Take a look at Syncfusion\Essential Suite\Grid\Samples\DataBound\FilterBarGrid sample.
You can use the custom option and based on condition like beginswith should be good to use.
Also refer KB :
How do I make my filter bar use textboxes and have the display respond to each keystroke?
Best regards,
Stanley