I have one case.
In accordance with documentation on the official site:
It’s possible to get consul_health_checks[check_name=“Vault Sealed Status”].passing metric from the Consul agent.
I’ve just configured Vault (1.6.1 version) with Consul Backend and Consul client agent (1.8.1 version).
Consul agent configuration includes section with metrics configuration for Prometheus:
Metrics are exposed and could be checked.
Unfortunately, there is no consul_health_checks metric or some other metric related to Vault sealed status.