PowerShell script to demonstrate how to make calls to SharePoint Online API using authorization token retrieved with PnP PowerShell

PnP-SharePointOnline-RestAPI-AuthAccessToken.ps1

<#
    PowerShell script to demonstrate how to make calls to SharePoint Online API using authorization token retrieved with PnP PowerShell
    This should work if the SharePoint tenant has LegacyAuthProtocolsEnabled as FALSE (legacy form based auth not authorized)
    You need to have SharePoint Online PnP PowerShell installed https://github.com/SharePoint/PnP-PowerShell
#>

$spoUrl = "https://<tenant>.sharepoint.com"

$connection = Connect-PnPOnline -Url $spoUrl -Credentials UserCredential -ReturnConnection

$AuthAccessToken = Get-PnPAppAuthAccessToken -Connection $connection

$headers = @{
    "Accept" = "application/json;odata=nometadata"
    "Authorization" = "Bearer $AuthAccessToken"
}

$apiEndpoint = "/_api/Web"
$apiUri = $spUrl + $apiEndpoint

$res = Invoke-RestMethod -Method Get -Uri $apiUri -Headers $headers