Get installed software from the local or remote machine by remotely querying the registry (NOT using Win32_Product)

Get-InstalledSoftware.ps1

function Get-InstalledSoftware {
    [cmdletbinding()]
    param(
        [parameter(ValueFromPipeline=$true,ValueFromPipelineByPropertyName=$true)]
        [string[]]$ComputerName = $env:ComputerName 
    ) 

    begin {
        $UninstallRegKey = 'SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall'
    } 

    process {

        foreach($Computer in $ComputerName) {

            if(Test-Connection -ComputerName $Computer -Count 1 -ea 0) {

                Write-Verbose "Working on $Computer"
                $operatingSystem = (Get-WmiObject -ComputerName $Computer -Class Win32_OperatingSystem).Caption
                if ((Get-WmiObject -Class Win32_OperatingSystem -ComputerName $Computer -ErrorAction SilentlyContinue).OSArchitecture -eq '64-bit') {
                    $RegistryViews = @('Registry32','Registry64')
                } else {
                    $RegistryViews = @('Registry32')
                }

                foreach($RegistryView in $RegistryViews) {
                    $HKLM = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine', $Computer, $RegistryView)
                    $UninstallRef = $HKLM.OpenSubKey($UninstallRegKey)
                    $Applications = $UninstallRef.GetSubKeyNames()

                    foreach ($App in $Applications) {
                        $AppRegistryKey = $UninstallRegKey + "\\" + $App
                        $AppDetails = $HKLM.OpenSubKey($AppRegistryKey)
                        $AppGUID = $App
                        $AppDisplayName = $($AppDetails.GetValue("DisplayName"))
                        $AppVersion = $($AppDetails.GetValue("DisplayVersion"))
                        $AppPublisher = $($AppDetails.GetValue("Publisher"))
                        $AppInstalledDate = $($AppDetails.GetValue("InstallDate"))
                        $AppUninstall = $($AppDetails.GetValue("UninstallString"))

                        if($AppDisplayName) {
                            New-Object PSObject -Property @{
                                ComputerName = $Computer.ToUpper()
                                AppName = $AppDisplayName
                                AppVersion = $AppVersion
                                AppVendor = $AppPublisher
                                InstalledDate = if($AppInstalledDate) {
                                    if($AppInstalledDate -notmatch '\d*/\d*/\d*') { 
                                        [datetime]::ParseExact($AppInstalledDate, 'yyyyMMdd', $null) 
                                    } else {
                                        Get-Date -Date $AppInstalledDate
                                    }
                                };
                                UninstallKey = $AppUninstall
                                AppGUID = $AppGUID
                            }
                        }
                    }
                }

            } else {
                Write-Warning "$Computer is unavailable"
            }
        }
    }
    end {}
}

# Example:
# Get-InstalledSoftware | Where { $_.InstalledDate } | Select-Object -First 4