This is just not possible as the Modeler will also tell you when you try to set a column "editable" on a Data Grid with a microflow as Data Source. Best bet is to see if you can rework your logic to remove the need for a microflow as the data grid datasource.
The datagrid should still be editable even when entities are being passed via microflow.
Is your datagrid set to editable? Is your datagrid contained into a dataview? - If the dataview is not editable, your datagrid will inherit that.
You could also have buttons for creating/editing individual rows. What exactly are you trying to achieve?
In mendix data grid, if the data source type is Microflow, you can't edit the grid columns. Even, you can see this error in the modeler error console .