How to collect custom inventory from Azure AD Joined devices

Use this powershell script and deploy it using intune.

Function Get-SystemSpecs { 
$processorSpecs = Get-CimInstance win32_processor 
$processorName = $processorSpecs.Name 
$processorSpeed = [string]([math]::round(($processorSpecs.CurrentClockSpeed /1000),2)) + 'ghz' 
$processorCores = $processorSpecs.NumberOfCores 
$processorThreads = $processorSpecs.ThreadCount 
$ramTotal = "{0:N2}" -f (((Get-CimInstance CIM_PhysicalMemory | select -ExpandProperty Capacity) | measure -Sum).sum /1gb )
	
	Function Get-RAMDetails	{
    $RAM = Get-CimInstance CIM_PhysicalMemory | where {$_.CreationClassName -like "Win32_PhysicalMemory"}
	$RAM = $RAM | ForEach{ $_.DeviceLocator + ": " + ($_.Capacity / 1GB) + "GB, " + ($(if ($RAM.SMBIOSMemoryType -eq "24"){"DDR3-"} ElseIf ($RAM.SMBIOSMemoryType -eq "26"){"DDR4-"} ElseIf ($RAM.SMBIOSMemoryType -eq "34"){"DDR5-"} Else {"Unknown-"}))  + $_.ConfiguredClockSpeed + "MHz" + " (" + $_.Manufacturer +")"} 
	If ($RAM.Count -gt 1) { $RAM = [String]::Join(", ",$RAM)}
	Return $RAM
} 

Function Get-HDDDetails { 
	$HDD = Get-CimInstance Win32_DiskDrive | where {$_.MediaType -like "Fixed*"} 
	$HDD = $HDD | ForEach{ $_.caption + ", Capacity: " + [math]::round(($_.Size / 1GB),'2') + "GB" } 
	If ($HDD.Count -gt 1) { $HDD = [String]::Join(", ",$HDD)}
	Return $HDD
}

$Specs = @{ 
	'ComputerName' = $env:ComputerName
	'Processor' = $processorName 
	'Cores' = $processorCores 
	'ThreadCount' = $processorThreads 
	'ProcessorClockSpeed' = $processorSpeed 
	'Physical Memory Size' = $ramTotal + ' GB' 
	'Memory chip(s)' = Get-RAMDetails
	'System Type' = Get-CimInstance win32_operatingsystem | select -ExpandProperty OSArchitecture 
	'Hard Drive(s)' = Get-HDDDetails 
	'Serial' = Get-CimInstance win32_bios | select -expandproperty serialnumber 
	'OS' = Get-CimInstance win32_operatingsystem | select -expandproperty caption 
    }
    Return $Specs 
} 

Get-SystemSpecs | ConvertTo-Json -Compress

Then use this graph api script to pull the hardware details returned by the powershell script.

# Set the required variables
$tenantId = "<Your Tenant ID>"
$clientId = "<Your Client ID>"
$clientSecret = "<Your Client Secret>"
$ScriptGUID = "<Your Script GUID>"
$URL = "https://graph.microsoft.com/beta/deviceManagement/deviceManagementScripts/$ScriptGUID/deviceRunStates?`$expand=managedDevice"

# Authenticate and get an access token
$body = @{
    Grant_Type    = "client_credentials"
    Scope         = "https://graph.microsoft.com/.default"
    Client_Id     = $clientId
    Client_Secret = $clientSecret
}

$tokenResponse = Invoke-RestMethod -Uri "https://login.microsoftonline.com/$tenantId/oauth2/v2.0/token" -Method Post -ContentType "application/x-www-form-urlencoded" -Body $body
$accessToken = $tokenResponse.access_token

# Retrieve the data from the specified endpoint
$headers = @{
    Authorization = "Bearer $accessToken"
    'Content-Type' = "application/json"
}

$response = Invoke-RestMethod -Uri $URL -Headers $headers -Method Get
$deviceRunStates = $response.value

# Prepare an array to hold the final data
$finalData = @()

foreach ($deviceRunState in $deviceRunStates) {
    $resultMessage = $deviceRunState.resultMessage | convertFrom-Json

    $finalData += [PSCustomObject]@{
        ComputerName      = $resultMessage.ComputerName
        Processor         = $resultMessage.Processor
        Cores             = $resultMessage.Cores
        ThreadCount       = $resultMessage.ThreadCount
        ProcessorClockSpeed = $resultMessage.ProcessorClockSpeed
        RamTotal          = $resultMessage.'Physical Memory Size'
        RamDetails        = $resultMessage.'Memory chip(s)'
        SystemType        = $resultMessage.'System Type'
        HardDriveDetails  = $resultMessage.'Hard Drive(s)'
        OS                = $resultMessage.OS
        Serial            = $resultMessage.Serial
        RunState          = $deviceRunState.runState
        ErrorCode         = $deviceRunState.errorCode
        ErrorDescription  = $deviceRunState.errorDescription
        LastStateUpdateDateTime = $deviceRunState.lastStateUpdateDateTime
    }
}

# Export the data to a CSV file
$finalData | Export-Csv -Path "C:\temp\IntuneDeviceRunStates.csv" -NoTypeInformation