In this article, I have included a script that uses Azure PowerShell Module to authenticate to Microsoft Graph API in PowerShell using Interactive Login.

Here are the steps:

• Install Azure AD PowerShell Module on your windows machine (if not installed already)
• Make sure Microsoft.IdentityModel.Clients.ActiveDirectory.dll and Microsoft.IdentityModel.Clients.ActiveDirectory.WindowsForms.dll are available on your windows machine
• Update your dll paths, tenant id, tenant name and site relative path in the script
• Execute script
• Use interactive login method and PowerShell client id to get an access token from ADAL
• Use access token to call the Microsoft Graph API to get site id for the given site relative path

I would like to thank Vardhaman Deshpande, for the sample PowerShell Script.

PowerShell Script

$Global:adDllPath = "C:\Program Files (x86)\WindowsPowerShell\Modules\Azure\5.1.2\StorSimple\Microsoft.IdentityModel.Clients.ActiveDirectory.dll"
$Global:adWinFormsDllPath = "C:\Program Files (x86)\WindowsPowerShell\Modules\Azure\5.1.2\StorSimple\Microsoft.IdentityModel.Clients.ActiveDirectory.WindowsForms.dll"

# Tenant specific values
$Global:spoTenantName = "YourTenantName"
$Global:spoTenantId = "YourTenantID"
$siteRelativePath = "/sites/dev"

# Let us use a well know Client Id known to Azure AD and reserved for PowerShell.
$Global:clientId = "1950a258-227b-4e31-a9cf-717495945fc2"
$Global:graphApiEndPointUrl = "https://graph.microsoft.com"
$Global:redirectUri = "urn:ietf:wg:oauth:2.0:oob"

$Global:spoAdminUrl = "https://$Global:spoTenantName-admin.SharePoint.com"
$Global:authority = "https://login.microsoftonline.com/$Global:spoTenantId"

function GetAuthResult {
    [System.Reflection.Assembly]::LoadFrom($Global:adDllPath) | Out-Null
    [System.Reflection.Assembly]::LoadFrom($Global:adWinFormsDllPath) | Out-Null

    $authContext = New-Object "Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContext" -ArgumentList $Global:authority
    $authResult = $authContext.AcquireToken($Global:graphApiEndPointUrl, $Global:clientId, $Global:redirectUri, "Auto")

    return $authResult
}

function GetSiteId {
    Param(
        [Parameter(Mandatory = $true)]
        [String]
        $Authorization,
        [Parameter(Mandatory = $true)]
        [String]
        $SiteRelativePath
    )

    $endpoint = "$Global:graphApiEndPointUrl/v1.0/sites/$Global:spoTenantName.sharepoint.com:$SiteRelativePath"

    $headers = @{
        'Content-Type'  = 'application/json'
        'Authorization' = $Authorization
    }

    $siteResult = (Invoke-RestMethod -Method Get -Uri $endpoint -Headers $headers)

    return $siteResult
}

$authResult = GetAuthResult

if ($authResult.AccessToken) {
    $authorization = "Bearer {0}" -f $authResult.AccessToken
    $siteResult = GetSiteId $authorization $siteRelativePath

    if ($siteResult.id) {
        Write-Host $siteResult.id
    }
    else {
        Write-Host $siteResult
    }
}
else {
    Write-Host $authResult
}