SharePoint Online: Add Person or Group (People Picker) Column to List using PowerShell

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Taxonomy.dll"

#Custom function to add column to list
Function Add-PersonOrGroupColumnToList()
{ 
    param
    (
        [Parameter(Mandatory=$true)] [string] $SiteURL,
        [Parameter(Mandatory=$true)] [string] $ListName,
        [Parameter(Mandatory=$true)] [string] $Name,
        [Parameter(Mandatory=$true)] [string] $DisplayName,
        [Parameter(Mandatory=$false)] [string] $Description=[string]::Empty,
        [Parameter(Mandatory=$false)] [string] $IsRequired = "FALSE",
        [Parameter(Mandatory=$false)] [string] $EnforceUniqueValues = "FALSE",
        [Parameter(Mandatory=$false)] [string] $SelectionMode="PeopleOnly"
    )

    #Generate new GUID for Field ID
    $FieldID = New-Guid

    Try {
        $Cred= Get-Credential
        $Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.Username, $Cred.Password)

        #Setup the context
        $Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
        $Ctx.Credentials = $Credentials
        
        #Get the List
        $List = $Ctx.Web.Lists.GetByTitle($ListName)
        $Ctx.Load($List)
        $Ctx.ExecuteQuery()

        #Check if the column exists in list already
        $Fields = $List.Fields
        $Ctx.Load($Fields)
        $Ctx.executeQuery()
        $NewField = $Fields | where { ($_.Internalname -eq $Name) -or ($_.Title -eq $DisplayName) }
        if($NewField -ne $NULL)  
        {
            Write-host "Column $Name already exists in the List!" -f Yellow
        }
        else
        {
            #Create Column in the list
            $FieldSchema = "<Field Type='User' ID='{$FieldID}' DisplayName='$DisplayName' Name='$Name' Description='$Description' Required='$IsRequired' EnforceUniqueValues='$EnforceUniqueValues' ShowField='ImnName' List='UserInfo' UserSelectionMode='$SelectionMode' />"
            $NewField = $List.Fields.AddFieldAsXml($FieldSchema,$True,[Microsoft.SharePoint.Client.AddFieldOptions]::AddFieldInternalNameHint)
            $Ctx.ExecuteQuery()    

            Write-host "New Column Added to the List Successfully!" -ForegroundColor Green  
        }
    }
    Catch {
        write-host -f Red "Error Adding Column to List!" $_.Exception.Message
    }
} 

#Set parameter values
$SiteURL="https://crescent.sharepoint.com"
$ListName="Projects"
$Name="ProjectMembers"
$DisplayName="Project Members"
$Description="Enter the Project Team Members"
$SelectionMode="PeopleOnly" #Or PeopleAndGroups

#Call the function to add column to list
Add-PersonOrGroupColumnToList -SiteURL $SiteURL -ListName $ListName -Name $Name -DisplayName $DisplayName -Description $Description -SelectionMode $SelectionMode 

#Parameters
$SiteURL = "https://crescent.sharepoint.com/sites/london" 
$ListName = "Desk Allocation"
$CSVFilePath = "C:\Temp\columns.csv"

Try {
    #Connect to PnP Online
    Connect-PnPOnline -Url $SiteUrl -Interactive

    #Get Data from CSV
    $ListColumns = Import-Csv $CSVFilePath

    ForEach($Column in $ListColumns)
    {
        Add-PnPField -List $ListName -Type User -InternalName $Column.Name -DisplayName $Column.Name -AddToDefaultView
        Write-Host "Added Column '$($Column.Name)' to the List!"
    }
} 
Catch {
    Write-Host "Error:"$_.Exception.Message
 }

$FieldSchema = "<Field Type='UserMulti' ID='{$FieldID}' DisplayName='$DisplayName' Name='$Name' Description='$Description' Required='$IsRequired' EnforceUniqueValues='$EnforceUniqueValues' ShowField='ImnName' List='UserInfo' UserSelectionMode='$SelectionMode' Mult='TRUE' />"

#Config Variables
$SiteURL = "https://crescenttech.sharepoint.com/sites/marketing"
$ListName= "Projects"

#Connect to PnP Online
Connect-PnPOnline -Url $SiteURL -Credentials (Get-Credential)

#Define XML Schema for User Field
$FieldXML= "<Field Type='User' Name='ProjectManager' ID='$([GUID]::NewGuid())' DisplayName='Project Manager' Required ='FALSE' UserSelectionMode='PeopleOnly'></Field>"

#Add User Field to list
Add-PnPFieldFromXml -FieldXml $FieldXML -List $ListName

$FieldXML= "<Field Type='UserMulti' Name='TeamMembers' ID='$([GUID]::NewGuid())' DisplayName='Team Members' Required ='FALSE' UserSelectionMode='PeopleAndGroups' Mult='TRUE' ></Field>"