Importing an OVF/OVA can be deployed to either a vCenter Server and/or Standalone ESXi endpoint.
Today, both Get-OvfConfiguration / Import-VApp assumes vCenter Server connection but this should not be a constraint or limitation as OVF/OVA import should also be possible when specifying ESXi host, especially useful for initial setup where vCenter Server does not exists (yet)
There is a massive benefit to VMware to have as many people as possible with manageable lab environments, this is really a powerful feature to support that goal.