Yeah, that is not how a regular datagrid works. You could try mimicking a datagrid in a list view which has widgets to support infinite scroll in the AppStore. But that infinite scroll widget for as far as I know does not call an MF to get the next set of results. So you might need to adjust it yourself.
I would lose the datagrid approach though as that widget is too rigid in my opinion to achieve your goal.
Feel free to reach out to me in the Mx community Slack to brainstorm some more about it.
I think you would have to build your own widget for this….
If you are comfortable with CSS, a list view would look better, but as Mitchel said, does not natively support calling a MF on “load more” so you would still have to use a separate button.
The best solution would probably be a custom plugable widget with repeating containment introduced in 8.7, but this will require you know React.