Hi
Sorry, If I misunderstanding your issue.
First, I don't think loading Million+ records on a Screen is a good idea. What is the use case for this?
Second, What is the original data source in this case? If you can control it(Access, Filter etc), You can expose an API. In the API to access the original datasource and fetch the smaller recordset you needed, then return it to the screen.
Furthermore, If possible you can implements API that supports pagination such as(e.g: top, skip )
Kind Regards