scannedps metric clarification/alternative


using mongodb community edition + datadog integration, I am trying to simulate the “Scanned / Returned” metrics offered by Atlas.
I was trying to use
mongodb.metrics.queryexecutor.scannedps / mongodb.metrics.document.returnedps

But when re-reading the documentation, it seems to me that the scannedps metrics actually corresponds to amount of items read from the index, not from the collection. So this would be equivalent to IXSCAN, but as far as I understand, to achieve the metric provided by Atlas, I would need the COLLSCAN value.

Is there an alternative metric. Have I misunderstood the meaning of the metrics provided by Atlas?