How would I: Monitor physical link status of an ESXi host from within a VM?

Scenario:

I run a virtualized SIEM on an ESXi 6.7 host and rely on the machines inside to monitor availability (I run a script every minute to pole a link provided to me by HealthChecks.io)

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This tells me a few things:

-That the internet at the site is up

-That the physical server is online (otherwise the VMs wouldn't be)

-That the VM is online

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We utilize a secondary NIC on the server to connect to a SPAN port on the client's switch. How do I monitor this, since it's connected at to the physical host and only passing through to the VM?

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My thought would be writing a script that polls the host via SNMP, but I am interested to see if the community has a better way I could try.