vRealize Network Insight Cloud collects many metrics for NSX policy manager including the firewall metrics.

Metric Name Metric API Name Description
Distributed Firewall Application Rules Count usage.distributedFirewallApplicationRuleCount.absolute.maximum.number Number of distributed firewall rules of category application.
Distributed Firewall Emergency Rules Count usage.distributedFirewallEmergencyRuleCount.absolute.maximum.number Number of distributed firewall rules of category emergency.
Distributed Firewall Environment Rules Count usage.distributedFirewallEnvironmentRuleCount.absolute.maximum.number Number of distributed firewall rules of category environment.
Distributed Firewall Ethernet Rules Count usage.distributedFirewallEthernetRuleCount.absolute.maximum.number Number of distributed firewall rules of category Ethernet.
Distributed Firewall Infrastructure Rules Count usage.distributedFirewallInfrastructureRuleCount.absolute.maximum.number Number of distributed firewall rules of category infrastructure.