Fr the current vCenter you could do
([uri](Get-AdvancedSetting -Entity $global:DefaultVIServer -Name 'config.vpxd.sso.admin.uri').Value).Host
If you are connected to all your vCenters you could do
$global:DefaultVIServers |Select @{N='vCenter';E={$_.Name}},
@{N='PSC';E={([uri](Get-AdvancedSetting -Entity $_ -Name 'config.vpxd.sso.admin.uri').Value).Host}}