I'm able to mute nodes using powershell, however it doesn't work with our ESXi hosts, which are actually discovered via VMAN. They do have NodeIDs though. Can I mute using NodeID?
I'm afraid you need the URI. Alert suppression is designed to work with multiple entity types, not just nodes, so an ID alone is not sufficient. There are details here:
Alerts · solarwinds/OrionSDK Wiki · GitHub
Fortunately, you can easily retrieve the URI for a node if you know the node ID.