I'm under the impression that within the hyperscalers (and probably the big colo/hosting firms, too), this is known. It's important to them, and customers, especially when a customer is trying to architect an HA or DR system and needs to ensure they don't inadvertently choose a region (or even a zone that isn't physically in the same place at other zones in the same region) that has "artificially" (can be for all kinds of legitimate reasons) latency from the primary zone.

This is not an uncommon scenario. My current employer specializes in SAP migrations to cloud and this is now a conversation we have with both AWS & GCP networking specialists when pricing & scoping projects... after having made incorrect assumptions and being bitten by unacceptable latency in the past.