Enabling a Standalone Host to Use a Software Specification
Starting with vSphere 8.0, you can use the vSphere Lifecycle Manager to manage the life cycle of standalone hosts in your vCenter Server system.
You can add a standalone host to a vCenter Server instance under a data center object or into a folder. See ESXi Hosts. If you remove a host from a cluster but leave it in the data center, the host is also considered a standalone host.
To manage a standalone host with a software specification, you must first enable the vSphere Lifecycle Manager on that host. You can run a preliminary check to establish whether the standalone host meets all requirements for enabling the vSphere Lifecycle Manager. Call the check_Task(host_ID, check_spec) method of the com.vmware.esx.settings.hosts.enablement.Software interface and pass as arguments the host identifier and a CheckSpec instance. The pre-checks that you can skip before enabling the vSphere Lifecycle Manager on a standalone host are the same as for a cluster.
To enable vSphere Lifecycle Manager on a standalone host, call the enable_Task(host_ID, check_spec) method of the com.vmware.esx.settings.hosts.enablement.Software interface. Pass as arguments the host unique identifier and optionally, a com.vmware.esx.settings.hosts.enablement.SoftwareTypes.EnableSpec instance to define whether the any checks can be skipped during the feature enablement operation. Currently, you can skip only the check for orphaned vSphere Installation Bundles (VIBs).