The pulling itself has never been a scaling/bottleneck concern in Prometheus, especially since no individual events are transferred, but just the current state

The pulling itself has never been a scaling/bottleneck concern in Prometheus, especially since no individual events are transferred, but just the current state of each metric. The bottleneck is usually the storage's sustained ingestion speed (disk IO or similar). A single big Prometheus server can easily do millions of time series, and in an older record, 800,000 samples stored per second. You could monitor e.g. 10,000 hosts with that with quite some detail, and the bottleneck is still not the pull aspect.