Try this, I think this gets you want you want,
# Import the Horizon module
Import-Module VMware.VimAutomation.HorizonView
# Establish connection to Connection Server
$hvServer = Connect-HVServer -server $hzConn -User $hzUser -Password $hzPass -Domain $hzDomain
$ViewAPI = $hvServer.ExtensionData
$query_service = New-Object "Vmware.Hv.QueryServiceService"
$query = New-Object "Vmware.Hv.QueryDefinition"
$query.queryEntityType = 'MachineSummaryView'
$machines = $query_service.QueryService_Query($ViewAPI,$query)
$machineInfos=$ViewAPI.Machine.Machine_GetInfos($machineIds)
foreach($machineInfo in $machineInfos)
{
if($machineInfo.ManagedMachineData.ViewComposerData.Operation -eq "PUSH_IMAGE")
{
Write-Host $machineInfo.Base.Name $machineInfo.ManagedMachineData.ViewComposerData.Operation $machineInfo.ManagedMachineData.ViewComposerData.OperationState $machineInfo.ManagedMachineData.ViewComposerData.BaseImagePath $machineInfo.ManagedMachineData.ViewComposerData.PendingBaseImageSnapshotPath
}
}
It shows the desktop name, the maintenance task, what the state is, and the pending parent image, and the pending snapshot. The ones I had returned where the only ones that where showing up as pending tasks in horizon.