This example illustrates how to edit DataGrid's row on a separate page.
The main idea is to open a new page and send the key value of the currently edited row as a parameter.
For this, create your own command button using the column's DisplayTemplate.
The navigation can be implemented using the default tag as it's demonstrated with the "Edit" button.
Another approach is using the default NavigationManager object. It's demonstrated in the "Save" and "Cancel" buttons on the SeparateEditForm page.