For better visibility from our community, I am pasting my answer from the ticket on the same topic:
I understand that this functionality might be important for your project, however, for the time being, it is not achievable with the Tag helpers.
When Html helpers are used, the list of data is passed as a parameter to the constructor of the Grid. This initializes the data configuration of the dataSource:
However, the Tag helpers have no constructor or a property that could do the same functionality.
Having said that, the only possible solution is to read the data as demonstrated in the demos.