Import non existing CSV rows to SharePoint online list

Hello Kaddrik,

One of the possible options would be something like this:

1. Get SharePoint List Items
2. Get CSV file
3. Compare two collections and identify the diff, items that are present in CSV but are not present in SharePoint list
4. Foreach diff item add it to the SharePoint

#Parameters
$SiteUrl = "https://m365x45097644.sharepoint.com/sites/Contoso"
$ListName = "ProjectList"
$CSVPath = "MyFile.csv"

#Get content
$CSVData = Import-CsV -Path $CSVPath #-Delimiter ";"

#Connection to site
Connect-PnPOnline $SiteUrl -UseWebLogin

$ListItems=(Get-PnPListItem -List $ListName ).FieldValues | Select-Object @{l="Title";e={$_."Title"}} , @{l="Department";e={$_."Department"}}, @{l="Project";e={$_."Project"}}

$Diff=Compare-Object -ReferenceObject $ListItems -DifferenceObject $CSVData | Where-Object {$_.SideIndicator -eq "=>"} | Select-Object -ExpandProperty InputObject

ForEach ($Row in $Diff)
{
    Write-Host "Adding Application $($Row.Title)"
    #Adds items
    Add-PnPListItem -List $ListName -Values @{"Title" = $($Row.Title);
                                              "Department"=$($Row.Department);
                                              "Project" = $($Row.Project);
   }
} 

Hope that helps.