High throughput prometheus compatible database like mimir, thanos, and the likes of GCP's managed prometheus really like metrics sent to them via remotewrite https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remotewrite. Grafana cloud for instance doesn't allow you to configure any scrape rules. The only option is to push metrics to them.

Currently Atlas only allows you to scrape metrics, which means for a user to get these metrics into a highly available version of Prometheus you need to relay this off of an intermediary process (prometheus exporter or a standalone prometheus server that supports scraping)

I think a good addition to this capability would be for mongo atlas to also support for pushing metrics to these types of Prometheus servers.