#Read more: https://www.sharepointdiary.com/2019/02/sharepoint-online-pnp-powershell-to-export-document-library-permissions.html#ixzz6i9Jb5Yj

Get-SPOFolderLibPerms.ps1

#Function to Get Permissions on a particular on List, Folder or List Item
Function Get-PnPPermissions([Microsoft.SharePoint.Client.SecurableObject]$Object)
{
    #Determine the type of the object
    Switch($Object.TypedObject.ToString())
    {
        "Microsoft.SharePoint.Client.ListItem"
        {
            If($Object.FileSystemObjectType -eq "Folder")
            {
                $ObjectType = "Folder"
                #Get the URL of the Folder
                $Folder = Get-PnPProperty -ClientObject $Object -Property Folder
                $ObjectTitle = $Object.Folder.Name
                $ObjectURL = $("{0}{1}" -f $Web.Url.Replace($Web.ServerRelativeUrl,''),$Object.Folder.ServerRelativeUrl)
            }
            Else #File or List Item
            {
                #Get the URL of the Object
                Get-PnPProperty -ClientObject $Object -Property File, ParentList
                If($Object.File.Name -ne $Null)
                {
                    $ObjectType = "File"
                    $ObjectTitle = $Object.File.Name
                    $ObjectURL = $("{0}{1}" -f $Web.Url.Replace($Web.ServerRelativeUrl,''),$Object.File.ServerRelativeUrl)
                }
                else
                {
                    $ObjectType = "List Item"
                    $ObjectTitle = $Object["Title"]
                    #Get the URL of the List Item
                    $DefaultDisplayFormUrl = Get-PnPProperty -ClientObject $Object.ParentList -Property DefaultDisplayFormUrl                    
                    $ObjectURL = $("{0}{1}?ID={2}" -f $Web.Url.Replace($Web.ServerRelativeUrl,''), $DefaultDisplayFormUrl,$Object.ID)
                }
            }
        }
        Default
        {
            $ObjectType = "List or Library"
            $ObjectTitle = $Object.Title
            #Get the URL of the List or Library
            $RootFolder = Get-PnPProperty -ClientObject $Object -Property RootFolder    
            $ObjectURL = $("{0}{1}" -f $Web.Url.Replace($Web.ServerRelativeUrl,''), $RootFolder.ServerRelativeUrl)
        }
    }
    
    #Get permissions assigned to the object
    Get-PnPProperty -ClientObject $Object -Property HasUniqueRoleAssignments, RoleAssignments
  
    #Check if Object has unique permissions
    $HasUniquePermissions = $Object.HasUniqueRoleAssignments
      
    #Loop through each permission assigned and extract details
    $PermissionCollection = @()
    Foreach($RoleAssignment in $Object.RoleAssignments)
    {
        #Get the Permission Levels assigned and Member
        Get-PnPProperty -ClientObject $RoleAssignment -Property RoleDefinitionBindings, Member
  
        #Get the Principal Type: User, SP Group, AD Group
        $PermissionType = $RoleAssignment.Member.PrincipalType
     
        #Get the Permission Levels assigned
        $PermissionLevels = $RoleAssignment.RoleDefinitionBindings | Select -ExpandProperty Name
  
        #Remove Limited Access
        $PermissionLevels = ($PermissionLevels | Where { $_ -ne "Limited Access"}) -join ","
  
        #Leave Principals with no Permissions
        If($PermissionLevels.Length -eq 0) {Continue}
  
        #Get SharePoint group members
        If($PermissionType -eq "SharePointGroup")
        {
            #Get Group Members
            $GroupMembers = Get-PnPGroupMembers -Identity $RoleAssignment.Member.LoginName
                  
            #Leave Empty Groups
            If($GroupMembers.count -eq 0){Continue}
            $GroupUsers = ($GroupMembers | Select -ExpandProperty Title) -join "; "
  
            #Add the Data to Object
            $Permissions = New-Object PSObject
            $Permissions | Add-Member NoteProperty Object($ObjectType)
            $Permissions | Add-Member NoteProperty Title($ObjectTitle)
            $Permissions | Add-Member NoteProperty URL($ObjectURL)
            $Permissions | Add-Member NoteProperty HasUniquePermissions($HasUniquePermissions)
            $Permissions | Add-Member NoteProperty Users($GroupUsers)
            $Permissions | Add-Member NoteProperty Type($PermissionType)
            $Permissions | Add-Member NoteProperty Permissions($PermissionLevels)
            $Permissions | Add-Member NoteProperty GrantedThrough("SharePoint Group: $($RoleAssignment.Member.LoginName)")
            $PermissionCollection += $Permissions
        }
        Else
        {
            #Add the Data to Object
            $Permissions = New-Object PSObject
            $Permissions | Add-Member NoteProperty Object($ObjectType)
            $Permissions | Add-Member NoteProperty Title($ObjectTitle)
            $Permissions | Add-Member NoteProperty URL($ObjectURL)
            $Permissions | Add-Member NoteProperty HasUniquePermissions($HasUniquePermissions)
            $Permissions | Add-Member NoteProperty Users($RoleAssignment.Member.Title)
            $Permissions | Add-Member NoteProperty Type($PermissionType)
            $Permissions | Add-Member NoteProperty Permissions($PermissionLevels)
            $Permissions | Add-Member NoteProperty GrantedThrough("Direct Permissions")
            $PermissionCollection += $Permissions
        }
    }
    #Export Permissions to CSV File
    $PermissionCollection | Export-CSV $ReportFile -NoTypeInformation -Append
}
    
#Function to get sharepoint online list permissions report
Function Generate-PnPListPermissionRpt()
{
    [cmdletbinding()]    
    Param 
    (   
        [Parameter(Mandatory=$false)] [String] $SiteURL,
        [Parameter(Mandatory=$false)] [String] $ListName,        
        [Parameter(Mandatory=$false)] [String] $ReportFile,
        [Parameter(Mandatory=$false)] [switch] $ScanItemLevel,
        [Parameter(Mandatory=$false)] [switch] $IncludeInheritedPermissions
    )
    Try {
        #Function to Get Permissions of All List Items of a given List
        Function Get-PnPListItemsPermission([Microsoft.SharePoint.Client.List]$List)
        {
            Write-host -f Yellow "`t `t Getting Permissions of List Items in the List:"$List.Title
   
            #Get All Items from List in batches
            $ListItems = Get-PnPListItem -List $List -PageSize 500
   
            $ItemCounter = 0
            #Loop through each List item
            ForEach($ListItem in $ListItems)
            {
                #Get Objects with Unique Permissions or Inherited Permissions based on 'IncludeInheritedPermissions' switch
                If($IncludeInheritedPermissions)
                {
                    Get-PnPPermissions -Object $ListItem
                }
                Else
                {
                    #Check if List Item has unique permissions
                    $HasUniquePermissions = Get-PnPProperty -ClientObject $ListItem -Property HasUniqueRoleAssignments
                    If($HasUniquePermissions -eq $True)
                    {
                        #Call the function to generate Permission report
                        Get-PnPPermissions -Object $ListItem
                    }
                }
                $ItemCounter++
                Write-Progress -PercentComplete ($ItemCounter / ($List.ItemCount) * 100) -Activity "Processing Items $ItemCounter of $($List.ItemCount)" -Status "Searching Unique Permissions in List Items of '$($List.Title)'"
            }
        }
 
            #Get the List
            $List = Get-PnpList -Identity $ListName -Includes RoleAssignments
             
            Write-host -f Yellow "Getting Permissions of the List '$ListName'..."
            #Get List Permissions
            Get-PnPPermissions -Object $List
 
            #Get Item Level Permissions if 'ScanItemLevel' switch present
            If($ScanItemLevel)
            {
                #Get List Items Permissions
                Get-PnPListItemsPermission -List $List
            }
        Write-host -f Green "`t List Permission Report Generated Successfully!" 
     }
    Catch {
        write-host -f Red "Error Generating List Permission Report!" $_.Exception.Message
   }
}
 
#region ***Parameters***

$SiteURL="https://cdmig.sharepoint.com/sharepoint/reports"
$ListName = "Common Reports"
$ReportFile="C:\Temp\ListPermissionRptItemLevel.csv"
#endregion
 
#Remove the Output report if exists
If (Test-Path $ReportFile) { Remove-Item $ReportFile }
 
#Connect to the Site
#Connect-PnPOnline -URL $SiteURL -Credentials (Get-Credential)
 
#Get the Web
$Web = Get-PnPWeb
  
#Call the function to generate list permission report
#Generate-PnPListPermissionRpt -SiteURL $SiteURL -ListName $ListName -ReportFile $ReportFile
Generate-PnPListPermissionRpt -SiteURL $SiteURL -ListName $ListName -ReportFile $ReportFile -ScanItemLevel
#Generate-PnPListPermissionRpt -SiteURL $SiteURL -ListName $ListName -ReportFile $ReportFile -ScanItemLevel -IncludeInheritedPermissions


#Read more: https://www.sharepointdiary.com/2019/02/sharepoint-online-pnp-powershell-to-export-document-library-permissions.html#ixzz6i9Jb5Yjd