Hi,
The limits to export from the visual itself are, for CSV the limit is 1m rows or 500MB
and for Excel, the limit depends on the number of fields you have selected on your dataset. The maximum is 100k rows but when you start adding more columns the number of rows exported decreases.
One option to have a 1m rows Excel of a visual is to schedule the report, do not send it on the email since that will have a maximum size of 10MB, but send it only as link via email, the user will be able to access it from the recent snapshots.
Hope this helps!
Kind regards,
Andres.