Add Everyoneone to SharePoint site

Add Everyoneone to external sharing site 

Connect-PnPOnline -Url <<SiteUrl>> -Interactive

$ReadOnlyUsers = @()

#

$testuser  = Get-PnPUser -Identity 8 #Need to get the id from Site collection Users hidden list

If($null -eq $testuser) {       

  $testuser = New-PnPUser -LoginName 'c:0-.f|rolemanager|spo-grid-all-users/afbb454f-58f1-48fc-8feb-bd15e2dd5c30'

}

$ReadOnlyUsers += $testuser.ID

Set-PnPListItem -List "PermissionMappings" -Identity 1 -Values @{User= $ReadOnlyUsers}